CHEK1 and hepatocellular carcinoma: 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.