Using the polymerase colony method to analyze the splice variants abundance, Butz, Roberta and Edwards found a 9.6-fold difference of (KRAS4B:KRAS4A) in SW480 cells and a 47-fold difference in PANC-1 cells compared to 1.4-fold difference in normal human colon, suggesting that expression of KRAS4A is lost in cancer (Butz et al., 2004). Here, KRAS is linked to cancer.