FIGURE 4:

The intrinsic activity of Mpk1(R68S) is dependent on the autophosphorylation of the TEY motif. mkk1∆mkk2∆ cells (A), mkk1∆mkk2∆pbs2∆ste7∆ cells (C), or Mpk1∆ cells (E) expressing the indicated Mpk1 molecules were plated in five dilutions on plates containing YPD supplemented with 15 mM caffeine (left) or on plates not containing caffeine (YNB –URA; right). Western blot analysis with the indicated antibodies was performed on protein lysates prepared from mkk1∆mkk2∆ cells (B), mkk1∆mkk2∆pbs2∆ste7∆ cells (D), or Mpk1 cells (F) expressing the indicated Mpk1 molecules.