Deng et al. (2009) and Zhou et al. (2018) found that BMP4 knockdown could ameliorate CRC cell migration, and invasion and overexpression of BMP4 enhance the invasiveness of Smad4-deficient human CRC cells. The findings of Yokoyama et al. (2017) suggest inhibition of autocrine BMP4 as a candidate treatment strategy for CRC. In our study, BMP4 expression (HR = 1.213, P = 0.02) was an independent risk factor for the prognosis of patients with CRC and was positively correlated with the infiltration abundance of M2 macrophages in tumor tissue (r = 0.28, P < 0.0001). The gene discussed is SMAD4; the disease is colorectal carcinoma.