Figure 9. (A) Overexpression of CPH1 induces white-opaque switching independently of the upstream MAP kinases Cek1 and Cek2.

White cells of strains containing the Tet-inducible STE11 ^ΔN467 allele in the indicated backgrounds were grown for 18 h in liquid Lee's medium at 30°C in the presence of doxycycline, diluted, and plated on Lee's agar plates without doxycycline to determine the percentage of opaque (black bars) and mixed white/opaque colonies (gray bars). Two independently constructed strains were tested in each case; the untransformed parental strain WO-1 served as control in two sets of experiments. Results are the means and standard deviations from three (cek1Δ and cek1Δ cek2Δ mutants) or six (wild-type strains) biological replicates. Only background switching frequencies were observed in all strains when the precultures were grown in the absence of doxycycline (not shown). (B) The scaffold protein Cst5 is not required for the induction of white-opaque switching by the hyperactive Ste11^ΔN467. White cells of strains containing a Tet-inducible wild-type STE11 or STE11 ^ΔN467 in wild-type or cst5Δ backgrounds were grown for 18 h in liquid Lee's medium at 30°C in the presence of doxycycline, diluted, and plated on Lee's agar plates without doxycycline to determine the percentage of opaque (black bars) and mixed white/opaque colonies (gray bars). Two independently constructed strains were tested in each case; the untransformed parental strain WO-1 served as control. Results are the means and standard deviations from three biological replicates. Only background switching frequencies were observed in all strains when the precultures were grown in the absence of doxycycline (not shown).