ATR and triple-negative breast carcinoma: Relative to a non-target control (siNT), siRNA-mediated knockdown of FBXW7 in the triple-negative breast cancer (TNBC) cell line MDA-MB-468 resulted in elevated cyclin E1, DNA damage as evidenced by increased γH2AX, and CHK1 pathway activation as measured by CHK1 phosphorylation at S317 (the ATR-mediated phosphorylation site), (Figure 1A).