Table 3.

Subtypes and comparisons of CAFs.

Subtype	Main gene	Function	Clinical significance
myCAF	ACTA2 (α-SMA), TAGLN, MYL9, CNN	High contractility, generating a large amount of ECM; It forms a physical barrier that hinders T cell infiltration and drug delivery; It is usually strongly activated by the TGF-β signaling pathway	It may be related to tumor hardness, invasion, metastasis and immune rejection
iCAF	IL6, LIF, CXCL12, CXCL1, CXCL2,	Secrete a large amount of cytokines and chemokines; Recruit myeloid cells and induce immunosuppression; Promote the stemness and survival of tumor cells; It is usually driven by the IL-1α/β and NF-κB signaling pathways.	It may be related to immunosuppression, inflammation and resistance to chemotherapy.
apCAF	CD74, MHC-II	It expresses MHC-II class molecules but lacks co-stimulatory molecule; It may mediate the impotence or inhibition of CD4+ T cells rather than their activation.	Unclear
meCAF	CAV1, ALDH1A	Metabolic reprogramming to support the metabolic needs of tumors; Nourish tumor cells through nutrients	It may be related to tumor growth, metabolic adaptation and treatment resistance.