CCL2 and neoplasm: CCL2 and CSF1 are essential in macrophage recruitment and polarization in the tumor microenvironment.19 As detected by quantitative RT-PCR (Fig. 6f) and western blot (Fig. 6g), CREBBP mutations and CREBBP knockdown resulted in significantly increased expression of CCL2 and CSF1 at transcriptional and protein levels in DB cells.