Chen et al (2000) postulated that the radiosensitising effects of gemcitabine might be related to p53 status. However, they concluded in their study on RKO-E6 and RKO-P colon cancer cell lines, which differed in p53 status, that it was not the single most important factor. Later, Robinson and Shewach (2001) studied related MCF-7 breast cancer cell lines with different p53 status and found no difference in radioenhancement by dFdC. This evidence concerns the gene TP53 and malignant colon neoplasm.