Figure 2.

Concentration-dependent activation of MAPKs by CuCl₂ and CdCl₂. Seedlings were exposed to increasing concentrations of CuCl₂ or CdCl₂ for 30 min. Protein extracts from roots were immunoprecipitated with M23, M11, M14, or M24 antibodies that are specific for SIMK, MMK2, MMK3, and SAMK, respectively. Subsequently, kinase activities were determined by in vitro kinase assays with γ-[³²P]ATP and MBP as substrate. The experiment was performed independently three times showing similar results.