PLK1 and breast cancer: As L1 displayed specific toxicity in a breast cancer cell line (figure 8), we further compared the synergistic effects of L1 and the Plk1 inhibitor between a cancer cell line (figure 9e) and a non-cancer cell line (figure 9f), with various doses of L1 in the absence (black) or presence (red) of 0.1 nM BI2536.