Four cell lines were assessed: SUM159-PT (TN; i.e., ERα-, PR-, and Her2-) cells, T47-D (luminal A; i.e., ERα+, PR+, and Her2-) cells, BT-474 (luminal B; ERα+, PR+, and Her2+) cells and HCC-1954 (Her2-like; ERα-, PR-, and Her2+) cells. This evidence concerns the gene ESR1 and hepatocellular carcinoma.