We and others have demonstrated a positive correlation of ACSL4 expression and aggressiveness in breast cancer cell lines, with the highest expression found in metastatic lines derived from triple negative (estrogen-receptor-α (ERα)-negative, progesterone-receptor (PR)-negative and not overexpressing human epidermal growth factor 2 receptor (HER2) protein) tumor breast cancer (e.g. MDA-MB-231 and Hs578T) [6, 9]. This evidence concerns the gene PGR and breast cancer.