CCL15 and colorectal carcinoma: In experimental metastasis models of SMAD4‐deficient compared to SMAD4‐proficient CRC, BMDCs were recruited to liver metastases through increased secretion of C‐C motif chemokine ligand (CCL)9 (mouse ortholog of CCL15), the ligand for the C‐C chemokine receptor type 1 (CCR1) receptor on myeloid cells.