Regulation of Bcl2 phosphorylation by stress response kinase pathway.

The anticancer drugs affecting either microtubule polymerization or depolymerization could trigger Bcl2 phosphorylation in mitotic phase of the cell cycle. By systematic site directed mutagenesis studies, we have previously mapped taxol induced phosphorylation sites to be Ser-70 and 87 residues of Bcl2 protein. Interestingly, sequences surrounding both serine-70 and serine-87 residues represent MAP kinase consensus motif. Since Bcl2 phosphorylation predominantly occurs at site consensus to MAP kinase family members, we were interested to test whether Erk2 or Jun kinase is involved in this pathway. Our in vitro studies document that stress activated kinase, JNK1 is responsible for Bcl2 phosphorylation.