FIG. 3.

MMS-induced can1^r mutations in various mutant strains. Cells were treated with MMS at the indicated concentrations for 20 min at 30°C, and following inactivation of the MMS, cells were plated on YPD medium for viability determination and on synthetic complete medium lacking arginine and containing canavanine for determination of the can1^r mutation frequency. Each curve represents the average of two or three experiments. (A) Elevated mutability in rad26Δ mutant strains lacking the APN1, APN2, and RAD14 genes required for the removal of AP sites. (B) Requirement of REV3 for mutagenesis in the apn1Δ apn2Δ rad26Δ and apn1Δ apn2Δ rad14Δ rad26Δ mutant strains. W.T., wild type.