HLA-G and breast cancer: Because estrogen receptor expression in locally advanced BC patients was associated with elevated non-vesicular HLA-G levels before CT (38) and functional studies also demonstrated that progesterone can stimulate HLA-G gene expression, the difference in levels and their prognostic relevance in these two BC cohorts may be explained in part by the absence of hormone receptors in TNBC and their presence in the majority of locally advanced BC patients (34, 44, 45).