MAPKAPK2 and infectious otitis media: Next, to demonstrate that it is specifically the macrophage MK2 activity that is sufficient to regulate Cxcl-12 expression in tumors, and therefore promote tumor progression and angiogenesis, we restored MK2 function by adoptive transfer of WT macrophages into the LysM-MK2-KO mice during AOM/DSS tumorigenesis.