E2F4 and neoplasm: On the other hand, the other reports focused genes that carry microsatellite-like repetitive motifs, i.e. mononucleotide runs, in their ORFs, such as TGFBR2, IGF2R, BAX, E2F4, MSH3, CASP5, TCF4 and PTEN. This may be based on the widely accepted viewpoint that destabilisation of the intragenic mononucleotide runs is frequently observed in microsatellite-unstable tumours, particularly in colorectal carcinomas (Schwartz et al. 1999).