TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Sequences: The polypeptide comprises an amino acid sequence having preferably at least 90% identity, preferably 97% identity with the mature polypeptide of SEQ ID NO: 2, or an amino acid sequence having preferably at least 60% identity, preferably at least 95% identity with the mature polypeptide of SEQ ID NO: 4. The polypeptide comprises or consists of the amino acid sequence of SEQ ID NO: 2 or 4; or its fragment having endoglucanase activity. The polypeptide comprises or consists of the mature polypeptide of SEQ ID NO: 2 or 4. The polypeptide is encoded by a polynucleotide which hybridizes under at least high stringency conditions with (i) the mature polypeptide coding sequence of SEQ D NO: 1, (ii) the cDNA sequence contained in the mature polypeptide coding sequence of SEQ ID NO: 1, or (iii) a complementary strand of (i) or (ii), or under preferably at least medium stringency conditions, more preferably medium-high stringency conditions, and most preferably high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 3, (ii) the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 3, or (iii) a complementary strand of (i) or (ii). The polypeptide is encoded by a polynucleotide comprising a nucleotide sequence having preferably at least 90% identity, preferably at least 97% identity with the mature polypeptide coding sequence of SEQ ID NO: 1, or a nucleotide sequence having preferably at least 60% identity, preferably at least 95% identity with the mature polypeptide coding sequence of SEQ ID NO: 3. The polypeptide is encoded by a polynucleotide comprising or consisting of SEQ D NO: 1 or 3; or its subsequence which encodes a polypeptide fragment having endoglucanase activity. The polypeptide is a variant comprising a substitution, deletion, and/or insertion of one or more amino acids of the mature polypeptide of SEQ ID NO: 2 or 4. The polypeptide is encoded by the polynucleotide contained in plasmid pPH47 which is contained in Escherichia coli NRRL B-W898 or plasmid pGIBG 146 which is contained in E. coli NRRL B-30901. The mature polypeptide is amino acids 19-396 of SEQ ID NO: 2 or amino acids 20-400 of SEQ ID NO: 4. The mature polypeptide coding sequence is nucleotides 110-1557 of SEQ ID NO: 1 or nucleotides 58-1200 of SEQ ID NO: 3. The polypeptide further has enzyme activity toward one or more substrates selected from xylan, xyloglucan, arabinoxylan, 1,4-beta-D-mannan, or galactomannan. The isolated polynucleotide comprises at least one mutation in the mature polypeptide coding sequence of SEQ ID NO: 1 or SEQ ID NO: 3, in which the mutant nucleotide sequence encodes the mature polypeptide of SEQ ID NO: 2 or 4, respectively. The dsRNA molecule is 15-25 or more duplex nucleotides in length. Preparation (claimed): Producing the polypeptide comprises cultivating a cell which in its wild-type form produces the polypeptide under conditions conducive for production of the polypeptide, and recovering the polypeptide. Alternatively, the method comprises cultivating a host cell comprising a nucleic acid construct comprising a nucleotide sequence encoding the polypeptide under conditions conducive for production of the polypeptide, and recovering the polypeptide. The method comprises cultivating the mutant cell or a cell comprising the mutant cell under conditions conducive for production of the protein, and recovering the protein. Producing a protein comprises cultivating the recombinant host cell under conditions conducive for production of the protein; and recovering the protein. Producing the polypeptide comprises cultivating a transgenic plant or a plant cell comprising a polynucleotide encoding the polypeptide having endoglucanase activity under conditions conducive for production of the polypeptide; and recovering the polypeptide. Preferred Mutant Cell: The mutant cell further comprises a gene encoding a native or heterologous protein. Preferred Method: Producing a polynucleotide comprising a mutant nucleotide sequence encoding a polypeptide having endoglucanase activity, comprises introducing at least one mutation into the mature polypeptide coding sequence of SEQ ID NO: 1 or 3, where the mutant nucleotide sequence encodes a polypeptide consists of the mature polypeptide of SEQ ID NO: 2 or 4; and recovering the polynucleotide comprising the mutant nucleotide sequence. Degrading or converting a cellulosic material comprises treating the cellulosic material with a composition comprising an amount of a polypeptide having endoglucanase activity or the host cell. The composition further comprises an amount of an endo-1,4-beta-glucanase, exo-1,4-beta-D-glucanase, and/or beta-D20 glycosidase. The composition further comprises an amount of one or more enzymes selected from hemicellulase, esterase, protease, laccase, or peroxidase. The method is a pretreatment process; a step in a simultaneous saccharification and fermentation process (SSF); or a step in a hybrid hydrolysis and fermentation process (HHF). The method further comprises recovering the degraded or converted cellulosic material. Producing a substance comprises saccharifying a cellulosic material with a composition comprising an amount of a polypeptide having endoglucanase activity or the host cell, fermenting the saccharified cellulosic material with one or more fermenting microorganisms, and recovering the substance from the fermentation. Steps (a) and (b) are performed simultaneously in a simultaneous saccharification and fermentation. The substance is an alcohol, organic acid ketone, amino acid, or gas. Inhibiting expression of a polypeptide in a cell comprises administering to the cell or expressing in the cell dsRNA molecule, where the dsRNA comprises a subsequence or portion of a polynucleotide encoding the mature polypeptide of SEQ ID NO: 2 or 4. SPECIFIC SEQUENCES - The polypeptide having endoglucanase activity ahs an amino acid sequence of SEQ ID NO: 2 or 4, respectively encoded by a polynucleotide having a nucleotide sequence of SEQ ID NO: 1 or 3.    EXAMPLE - No suitable example given.