BMP4 and cancer: Several studies have shown that BMP signaling plays a role in tumor delay in CRC cells themselves.26–29 By contrast, BMP signaling has recently been reported to promote the growth of xenograft tumors derived from primary human CRC, and autocrine BMP4 signaling has been identified as a therapeutic target in CRC.30,31 These controversies may be attributed to the heterogeneity of cancer and its microenvironment.