FIG. 6.

Hsp25 phosphorylation in vitro and in vivo. (A) Cell lysates from wild-type (wt) and MK2- and MK5-deficient MEFs which were left nonstimulated (lanes C) or were stimulated by arsenite treatment (250 μM for 45 min) (lanes Ars) were incubated in vitro with recombinant Hsp25 and [γ-³²P]ATP, and Hsp25 phosphorylating activity was detected by phosphorimaging. (B) 2D phosphoproteomics of wild-type and MK2- and MK5-deficient cells before and after stimulation by arsenite. The spot for phospho-Hsp25 was identified by mass spectroscopy and is indicated by an arrowhead. The autoradiograms shown are representative of the results of four separate experiments.