PGRMC1 and breast cancer: To investigate the PGRMC1 signalling mechanism implicated in breast cancer growth and progression, we used the chemical inhibitor AG-205; this aromatic compound has high-affinity binding to PGRMC1 and is able to disrupt the PGRMC1–heme complex axis as shown by spectroscopic properties.28 AG-205 has also been shown to inhibit PGRMC1’s downstream signalling.27,29 Findings yielded by our studies demonstrate that disrupting PGRMC1 signalling by AG-205 promotes apoptosis, whereas it inhibits the cell cycle, migratory and invasive capabilities of both ER-positive and TNBC cell lines.