To investigate whether this regulatory effect of TMUB1 on PD-L1 influences the immune escape of tumor cells, a T cell killing assay was performed using wild-type and stable TMUB1-knockdown MDA-MB-231 and MDA-MB-468 breast cancer cell lines co-cultured with activated peripheral blood mononuclear cells (PBMCs). The gene discussed is CD274; the disease is breast cancer.