MAPKAPK3 and neoplasm: Here we describe a novel role for members of the stress-activated protein kinase (p38 MAPK) signaling pathway, MAPKAPK2 (MK2) and MAPKAPK3 (MK3) (Cargnello and Roux, 2011), in mediating Beclin 1 S90 phosphorylation, which we show is essential for its autophagy and tumor suppressor function.