NOVELTY - A recombinant yeast cell comprising (a) butanol biosynthetic pathway and at least one genetic modification that increases the activity of the high osmolarity/glycerol response pathway, or (b) butanol biosynthetic pathway and at least one heterologous PBS2 protein encoding gene, is new. The butanol biosynthetic pathway comprises at least one gene that is heterologous to the yeast cell.    USE - The recombinant yeast cell, preferably Saccharomyces, Schizosaccharomyces, Hansenula, Candida, Kluyveromyces, Yarrowia or Pichia is useful for producing 1-butanol, 2-butanol and isobutanol, and improving fermentative production of butanol (all claimed) useful as industrial chemical, fuel additive, feedstock chemical in plastics industry, and food grade extractant in food and flavor industry.    ADVANTAGE - The cell has at least 40% improvement in growth yield in 1 weight/volume% isobutanol as compared to parental cell having no increase in activity of the high osmolarity/glycerol response pathway. The recombinant yeast cell has increased tolerance to butanol as compared with yeast cell that lacks the genetic modification.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method for producing 1-butanol, 2-butanol or isobutanol, involves growing the recombinant yeast cell under conditions suitable for production of 1-butanol, 2-butanol or isobutanol and optionally recovering the 1-butanol, 2-butanol or isobutanol;    (2) method for producing recombinant yeast cell having increased tolerance to butanol; and    (3) method for improving fermentative production of butanol, involves providing recombinant yeast cell comprising butanol biosynthetic pathway chosen from 1-butanol biosynthetic pathway, 2-butanol biosynthetic pathway and isobutanol biosynthetic pathway, where the yeast cell also comprises at least one genetic modification that increases activity of the high osmolarity/glycerol response pathway and the genetic modification increases PBS2 mitogen-activated protein kinase activity, and contacting the yeast cell with fermentable sugar, where the yeast cell produces butanol and the yeast cell has improved tolerance to the butanol as compared to yeast cell without at least one genetic modification that increases activity of the high osmolarity/glycerol response pathway and increases PBS2 mitogen-activated protein kinase activity.