CXCR4 and cancer: Moreover, both of the cell lines were characterized by lower expression of claudin-2 (CLDN2), C-X-C chemokine receptor type 4 (CXCR4), and cytochrome P450 family 24 subfamily A member 1 (CYP24A1), which codify for proteins commonly reported to be associated with cancer progression and invasiveness [62,63,64].