Quantitative RT–PCR confirmed that the E2F3 transcript level was increased in cancer (2.22-fold, log 2 scale; P=1.26 × 10−7, Student's t-test) and that the average RB1/E2F3 ratio was reduced by −0.87-fold (log 2 scale) from normal mucosa to cancer (P=3.52 × 10−6, Student's t-test). Here, RB1 is linked to cancer.