Provided herein is an inhibitor for decreasing cellular levels X-box-binding protein 1 variant 1 (Xv1) in a cancer cell and a method for decreasing Xv1 in a cancer cell by contacting the cancer cell with this inhibitor. Also provided is a pharmaceutical composition for treating a cancer and a method for treating a cancer by administering this composition. In addition there is provided a kit for targeting Xv1 with at least one Xv1 inhibitor, at least one pharmaceutically acceptable carrier and a means for detecting the Xv1 protein or mRNA.