In agreement with an earlier report [31], we did not observe an association between APOBEC3B expression in breast cancer cell lines and sensitivity to CHK1 inhibitors AZD7762 (ρ = − 0.198, padj = 0.8660, n = 33, Ntests = 26,610) or Calbiochem 681,640 (ρ = 0.143, padj = 0.933, n = 40, Ntests = 26,610, data not shown), and no other correlations between gene expression and log(IC50) in breast cancer cell lines were statistically significant. The gene discussed is CHEK1; the disease is breast cancer.