Loss of gef1 function restores polarized growth to scd1low tea1Δ cells. mCherry-Bgs4 distribution and cell morphology in tea1Δ, gef1Δ, tea1Δ gef1Δ and tea1Δ gef1-EANA cells, all in a scd1low cdc2-asM17 mCherry-bgs4 genetic background. Bgs4 on the plasma membrane indicates sites of growth. Cells correspond to those shown in Fig. 4A. scd1 expression was repressed by thiamine addition 24 hr prior to start of imaging. Cdc2 kinase activity was inhibited by 3-BrB-PP1 addition 30 min before imaging. A transient loss of Bgs4 from cell tips is seen in some scd1low gef1 mutant cells (~20%), including some of the examples shown in the movie; the reasons for this are not completely clear. Time interval during acquisition, 10 min; total elapsed time, 420 min; time compression at 15 frames per second playback, 9000X.