Fig. 2

Correlation between ERα and CHK1 and CHK2 activation status. A Volcano plot showing the protein expression as a function of the p-value of the indicated proteins (i.e., ERα—red, CHK1—blue and CHK2 – purple) in ERα-negative or ERα-positive tumors as indicated in the breast cancer landscape [3] and downloaded by https://www.breastcancerlandscape.org/. B Level of ERα S118 phosphorylation (yellow), CHK1 S345 phosphorylation (blue), and CHK2 T68 phosphorylation (purple) in ERα-negative or ERα-positive breast cancer cell lines. Significant differences were obtained by unpaired two-tailed Student’s t-test. °°°° (p < 0.0001) indicates significant differences in ERα S118 phosphorylation between ERα-negative or ERα-positive breast cancer cell lines. °°° (p < 0.001) indicates significant differences in CHK2 T68 phosphorylation between ERα-negative or ERα-positive breast cancer cell lines. * (p < 0.05) indicates significant differences in CHK1 S345 phosphorylation and CHK2 T68 phosphorylation in ERα-positive breast cancer cell lines. Linear regression and Spearman Correlation values (r) between ERα S118 phosphorylation and CHK2 T68 phosphorylation (C) or ERα S118 phosphorylation and CHK1 S345 phosphorylation (D) in ERα-positive breast cancer cell lines classified as luminal A (LumA – green) or luminal B (LumB – orange). r and p values are given in the main panel. Z scores for the antiproliferative effects of either ERα (red), CHK1 (blue), or CHK2 (purple) depletion by CRISPR/CAS9 (E) or small interference RNA (siRNA) (F) in ERα-positive breast cancer cell lines. The dotted lines represent the threshold for cell line sensitivity in each kind of procedure. Plots in (B-F) have been generated by downloading the experimental data by the Broad Institute through the DepMap portal https://depmap.org/portal. Each dot of the plots in (B-F) represents the value of the indicated parameter in a single breast cancer cell line. Crude data are given in supplementary table 1