Figure 4.

MAPK activation in response to flg22 peptide. Crude protein extracts were prepared from 14-d-old seedlings and subjected to an in-gel kinase assay using myelin basic protein as the embedded substrate. Kinase activity corresponding to MPK3, MPK4, and MPK6 is indicated. Seedlings were harvested at the indicated number of minutes following flg22 treatment. 0, No flg22 treatment. A, mekk1 mutant versus wild type. B, mekk1 + MEKK1, mekk1-1 mutant stably transformed with the wild-type MEKK1 gene. mekk1 + K361M, mekk1-1 mutant stably transformed with MEKK1 (K361M).