Hog1p phosphorylation level and growth phenotypes for the wild type (WT) and mutant yeast cells under various osmotic and salt stress conditions.

<p>A. Hog1p MAPK phosphorylation (P-Hog1p) was detected in the <i>ssk1Δste11Δ</i> mutant under hyperosmotic stress. Cells were exposed to different level of osmotic stress induced by sorbitol (concentration shown) in YPD medium for the time indicated. B. Same experiment as in A but for the wild type strain which shows higher sensitivity and a longer duration of the response. C. Hog1p phosphorylation was not detected in the <i>ste11Δssk2Δssk22Δ</i> mutant. D. Hog1p phosphorylation assay under ionic osmotic stress in the <i>ssk1Δste11Δ</i> double mutant. Cells were exposed to a different levels of salt stress induced by NaCl (concentration shown) in YPD medium for the time indicated. E. Same as in D but for the wild type cells. F. The <i>ssk1Δste11Δ</i> mutant exhibited better growth than <i>hog1Δ</i> mutant under osmotic stress. Serial dilutions (from left to right in each panel) of indicated strains were spotted onto YPD and salt plates and growth was scored after 3 days.