To explore the mechanisms underlying RhoA-regulated chemoreistance, Western blot was performed to determine the expression of p-glycoprotein(P-gp) and multidrug resistance-associated protein 1(MRP1), two membrane transport proteins known to mediate drug efflux, in CPT-11-resistant CRC cells and parental cells. This evidence concerns the gene ABCB1 and colorectal carcinoma.