The pfa4Δ mutant strain exhibits ras1-like defects at high temperature. (A) Overnight cultures of wild-type (WT; H99), akr1Δ (CBN134), pfa3Δ (CBN198), pfa5Δ (CBN124), pfa4Δ (CBN201), erf2Δ (DPG1), cpt6Δ (SKC7), cpt7Δ (CBN414), ras1Δ (CBN336), and erf4Δ (KMP1) strains and the reconstituted pfa4Δ/PFA4 (CBN324) mutant strain were serially diluted, spotted onto YPD medium, and incubated at 30°C, 37°C, and 39°C for 48 h. (B) Overnight cultures of the wild-type (H99) strain and ras1Δ (CBN336) and pfa4Δ (CBN201) mutant strains were diluted in YPD liquid medium and shifted to either 30°C or 37°C for 4 h. Cells were imaged (magnification, ×100) with DIC optics to assess temperature-dependent alterations in cell size and morphology. Scale bar, 5 μm.