ABCB1 and malignant colon neoplasm: Finally, inhibition of MARCKS phosphorylation sensitizes colon cancer cells to doxorubicin or 5-FU-based chemotherapy by decreasing ATP-binding-cassette transporter family member ABCB1 internalization [77], thereby reducing ABCB1 activity, a major cause of chemotherapy resistance in cancer [78,79].