PGR and breast cancer: The proliferation of breast cancer cells (MCF-7, BT-474, MDA-MB 231, and MDA-MB 468) can be suppressed by ALA at concentrations ranging from 20 to 200 μM by downregulating the expression of proteins such as cyclin-D1, progesterone receptor, and caveolin-1, and by upregulating the expression of estrogen receptor [56,57].