IDO1 and breast cancer: In this study, during the preparation of the IDO gene expression vector, we identified IDO gene expression in the human breast cancer cell lines MDA-MB-231, MDA-MB-435S, MDA-MB-453, SK-Br-3, T47D, ZR-75-1 and normal breast cells HBL-60; the gene was highly expressed in MDA-MB-435S, T47D, MCF-7.