CCL15 and colorectal carcinoma: Besides, collagen triple helix repeat containing 1 (CTHRC1), a protein highly expressed in CRC, can upregulate chemokine (C-C motif) ligand 15 (CCL15) via the TGF-β/Smad signaling pathway, enhancing TAM infiltration and creating a feedback loop that further propels the disease progression (Liu et al., 2024).