SMAD4 and colorectal carcinoma: Recently, we have found that loss of SMAD4 from CRC cells results in the secretion of CXCL1 and CXCL8 to recruit CXCR2+ neutrophils, and that, in turn, the recruited neutrophils abundantly produce CXCL1 and CXCL8, which further prompts the accumulation of CXCR2+ neutrophils and results in an amplification of the cytokine/chemokine milieu shaped by the CXCL1/8-CXCR2 axis [62].