Missense mutations of K-RAS codon 20 in human cancers have not been previously reported, however, mutations giving rise to phenylalanine incorporation into K-RAS codon 19 have been described previously in seven individual human colorectal cancers, a single human lung adenocarcinoma sample and a single lymphoblastic leukaemia [17-20]. Here, KRAS is linked to acute lymphoblastic leukemia.