TP53 and colorectal cancer: We have 7 patients each with more than 3 mutations (Figure 3), and when we look at these 7 samples, we can clearly see evidence of the generally accepted pathway of colorectal cancer progression: APC, as the first event, is found in 5/7; KRAS, a later event, in 6/7; and TP53, the last step to a carcinoma, is found in half of the samples.