MRC1 and cancer: Most of the M.Sig model genes are not included in the above 13 immune gene signatures.[25, 27] MRC1 is considered a marker of M2 macrophages, and lapatinib (tyrosine kinase inhibitor) can downregulate its expression, thereby eliminating the invasion and migration of cancer cells mediated by M2 polarized macrophages.[28] To explore the potential mechanism by which the M.Sig model can predict immunotherapeutic response, we divided macrophages into eleven subgroups and compared differences between them and their relationship with the M.Sig model.