SMAD4 and colorectal carcinoma: Immature myeloid cells positive for C‐C chemokine receptor type 1 (CCR1) have been linked to CRC progression and liver metastasis (Kitamura et al., 2007, 2010), in a mechanism that involves the loss of SMAD4 in CRC cells, triggering CCL15‐mediated recruitment of CCR1+ myeloid cells (Hirai et al., 2014; Itatani et al., 2013).