Additionally, a study on breast cancer [42], indicated that FAP+PDGFRβ+ CAF in tissues not only released CXCL12 to promote the migration of CD4+CD25+ T cells, but also expressed CD73, dipeptidyl peptidase IV (DPP4) and B7H3 to promote the conversion of CD4+ T cells to FOXP3+ Treg cells. Here, DPP4 is linked to breast cancer.