SP1 and malignant colon neoplasm: Moreover, treatment of RKO, SW480, HT-29 and HCT116 colon cancer cells with 5 or 10 mM aspirin for 24 or 48 hr also decreased expression of several gene products regulated by Sp1, Sp3 and Sp4 [24]–[29] and these include VEGF, VEGFR1, cyclin D1 and c-MET proteins (Figs. 2C and 2D), and the effects of aspirin on their expression were both concentration- and time-dependent.