KRAS and colorectal cancer: However, due to the genetic heterogeneity within colorectal cancer, a multitarget assay panel (e.g. mutations of k-ras, p53 and APC genes, as well as Bat-26 (a microsatellite instability marker) and highly amplifiable ‘long’ DNA) has to be screened to reach high sensitivities (63–95%) (Ahlquist et al, 2000; Tagore et al, 2003).