Its transcriptional activity was regulated by MAPK effector Egr-1, which could be activated by RTK ligands or mutant HRAS [7, 8], on the other hand, both LY294002 and wortmannin, inhibitors of PI3K, could efficiently down-regulate KLF5 promoter transcriptional activity in DLD-1 colorectal cancer cells [21]. The gene discussed is HRAS; the disease is colorectal cancer.