CHI3L1 and small cell lung carcinoma: In particular, SCLC CTCs recruit TAMs and stimulate the secretion of chitinase-3-like-1 (CHI3L1), vascular endothelial growth factor (VEGF), and matrix metalloproteinase-9 (MMP9), enabling SCLC CTCs to disseminate bypassing the mesenchymal phase [37].