MAPKAPK2 and neoplasm: We show here that MK2 regulates Cxcl-12 expression in tumor-infiltrated macrophages, as both myeloid and whole-body MK2 KO mice show deficient Cxcl-12 expression in colon tumors, and adoptive transfer of WT macrophages into myeloid-MK2 KO mice is sufficient to restore Cxcl-12 expression levels, tumor angiogenesis and tumor progression (Figures 4C–E).