For example, while studies have reported increased TS mRNA expression in human colorectal tumours from individuals with 3R/3R genotype, the only study of TS protein activity reported an increased activity in tumours harbouring the 3R/2R genotype, indicating the existence of additional post-transcriptional regulatory pathways (Etienne et al, 2002). Here, TYMS is linked to colorectal neoplasm.