By decreasing cholesterol and lipid raft levels in the plasma membrane, proprotein convertase subtilisin/kexin type 9 (PCSK9) boosts human epidermal growth factor receptor 1 and 3 (EGFR and HER3) activation, driving tumor growth and metastasis in triple‐negative breast cancer (TNBC). This evidence concerns the gene ERBB3 and neoplasm.