ESR1 and breast cancer: In addition to these TLK2-amplified breast cancer cell lines, we also selected a ER+/Her2− luminal breast cancer cell line with moderately high TLK2 but without TLK2 amplification (CAMA1), a TLK2-low ER+/Her2− luminal breast cancer (ZR75-1), and two benign epithelial cell lines (MCF12A and MCF10A).