Modeling recurrent mutations in CRC, a group induced five cDNAs and knockdown siRNAs as transgenes in the fly hindgut, including KRAS (fly ras), TP53 (p53), PTEN (pten), SMAD4 (Med), and APC (apc) by using the byn (brachyenteron) enhancer/promoter (Table 1). Here, SMAD4 is linked to colorectal carcinoma.