CCL2 and neoplasm: Indeed the pro-apoptotic phenotype of Y861F CM was reduced by the addition of exogenous recombinant MCP-1 to the pericyte CM (Fig. 4b), suggesting that the reduction of MCP-1 in Y861F pericytes is at least partially involved in the pro-apoptotic phenotype in tumours grown in PdgfrβCre + ;FAKY861F/Y861F (Y861F) mice.