A good correlation between CDC6 and CHEK1 mRNA expression levels in colon (R2 = 0.412), HCC (R2 = 0.673), lung (R2 = 0.597) and ovarian (R2 = 0.525) but not breast (R2 = 0.099) cancer (Fig. 7b and Supplementary Fig. S7) was identified from mRNA expression datasets of patient derived material in the Gene Expression Omnibus (GEO) database. This evidence concerns the gene CHEK1 and cancer.