CSF1 and neoplasm: More importantly, when macrophages express CSF-1R, tumor cells secrete M-CSF to attract TAMs,108 and after TAMs are attracted to tumor cells, they secrete EGF, which activates the epidermal growth factor receptor (EGFR) signaling pathway in tumor cells, and the activation of the EGFR pathway results in the extension of more pseudopods in tumor cells.101 Since myeloid cells are highly mobile and less compact, tumor cells combined with TAMs can gain stronger metastatic ability and are more likely to metastasize to the distal end.