CXCR4 and malignant colon neoplasm: Utilizing three different xenograft models of colon cancer cells that are either expressing surface CXCR4 (HT-29) or are null for the CXCR4 surface expression (DLD-1, HCT-116), we provided strong evidence that knockdown of CXCR4 results in reduced tumor growth and paclitaxel sensitization irrespective of their surface expression status (Fig. 5 and Fig. S1).