Next, to evaluate if CHK1 inhibition could be a possible pharmacological target [35–37] also in ERα-positive BCs, we inspected the DepMap datasets regarding the sensitivity of diverse BC cell lines to diverse CHK1 inhibitors that are in clinical trials (i.e., AZD; MK; prexasertib – Prexa; PF-477736 – PF; Ly-2603618 – Ly; PD-407824 – PD; CHIR-124 – CHIR; SB-218078—SB) [35–37]. This evidence concerns the gene CHEK1 and breast cancer.