The three slow-growing variant sublines of Yoshida sarcoma, LY-7, LY-5, and LY-336, synthesized in vitro approx. 3-4-fold more glycogen from exogenous glucose-14C than the parent tumor; this activity roughly paralleled the increasing survival time of the sublines.The glyconeogenic activity of the sarcoma as determined by the incorporation of carbon-14 from pyruvate-14C into glycogen was enhanced by ∼6-fold by the addition of glucose (10 mM); this glucose-stimulated glyconeogenesis was depressed by approx. 4-5-fold by the presence of inorganic phosphate (85 mM).Yoshida sarcoma variant LY-336, the slowest-growing tumor, showed a greater glyconeogenic activity than any of the other 3 tumors.No significant difference was observed in the glycolytic and glucose-oxidizing activity of the 4 strains of the tumor.The possible significance of these findings is discussed in relation to the biol. characteristics of these variant sublines.21 references.