Q-MT bundle elongation allows cell polarity reestablishment upon quiescence exit. (A) Quiescence exit of cells expressing the indicated polarity markers was triggered in the absence or presence of MBC. Numbers indicate the percentage of cells with polarized markers at the cell tips (N = 2 experiments and n > 200). Time is in minutes. (B–F) Cell shape is drastically impaired when the Q-MT bundle elongation is inhibited. (B) Cell shape was analyzed before and after refeeding of 5-d-old WT cells in the absence or presence of MBC. Control experiments were done in proliferating cells. Representative cells are shown. (C) Upon quiescence exit, the alp14Δ mutant is unable to elongate the Q-MT bundle and display massive cell shape defects associated with Tea1-GFP mislocalization. Alp14Δ cells expressing either GFP-Atb2 or Tea1-GFP are shown before and after cell refeeding. Cell shape was analyzed before and after refeeding or as a control in proliferation. (D) Control experiment in which tubulin is revealed by immunofluorescence using Tat1 antibodies in both WT and alp14Δ mutant cells in quiescence (5 d) and 2 h after quiescence exit. (E) After 5 d in YPD, mto1Δ-expressing GFP-Atb2 cells display a long and dynamic MT structure that is destabilized by a cold treatment (4°C for 24 h). When mto1Δ cold-treated cells are shifted back to 30°C and then refed, they do not assemble cytoplasmic MT until cells undergo mitosis. Graphs illustrate the number of MT bundles per cell. Data shown are from a single representative experiment out of four repeats (with n > 200 for each time point). The corresponding images are shown. (F) Cell shape of cold-treated mto1Δ cells was monitored upon quiescence exit. For all graphs, means and SDs are indicated. Bars, 2 µm.