We first screened a range of human CRC cell lines (HT-29; adenocarcinoma, T84; CRC lung metastasis, HRT-18; ileocecal adenocarcinoma, SW480; primary adenocarcinoma, and SW620; secondary adenocarcinoma lymph node metastasis) for their endogenous expression of CXCR4 and CD26 using a radioimmunobinding assay, and evaluated possible changes in each marker in response to exposure to chemotherapeutic agents. The gene discussed is CXCR4; the disease is colorectal carcinoma.