NRP1 and breast cancer: In mouse tumor model, injection of MCA-38 colon adenocarcinoma cells causes enrichment of neuropilin-1- (Nrp1-) pTreg cells, whereas that of 4T1 breast cancer cells causes enrichment of Nrp1+ tTreg cells, suggesting that both tTreg and pTreg cells can be enriched in the TME depending on the types of tumor [46].