Figure 6.

MAPKAPK2 is a downstream effector of p38α and the R49/149K non-methylation mutation reduces the interaction of p38α with MAPKAPK2. The wild-type and R49/149K mutant p38α proteins were expressed in p38α KD cells. Cells were stimulated with AraC and Flag-p38α was immunoprecipitated using anti-Flag antibodies. The interacting proteins were analyzed by mass spectrometric analysis. MAPKAPK2 was identified as an interactor of the p38α by Ingenuity Pathway Analysis (IPA). AraC-induced erythroid differentiation was reduced in MAPKAPK2 knockdown (KD) cells (A). The ectopic expression of p38α rescued differentiation of MAPKAPK2 KD1 cells (B). The Flag-p38α WT and R49/149K proteins were immunoprecipitated after AraC stimulation. MAPKAPK2 interacted with wild-type p38α; however, the R49/149K mutant exhibited a significantly lower interaction with MAPKAPK2, as examined by Western Blotting (C). PRMT1 promoted the interaction of wild-type p38α with MKK3 and MAPKAPK2 (D). The intensity of protein bands in Western Blots were quantified by Multi-Gauge V3.0 analysis. All results shown are representatives of three independent experiments. Statistical analysis was performed with results from three separate experiments. *** p < 0.005.