The KAI1/CD82 protein is a member of TM4SF (transmembrane 4 superfamily) and is located on human chromosome 11p11.2.[22] It was originally thought to be an inhibitory gene for metastasis of prostate cancer cells.[22,23] It mediates between cells as well as signal transduction between cells and ECM to exert biological effects.[24] Many studies have shown that reduced KAI1/CD82 expression may be a useful marker for many human tumors metastases, invasion, and prognostic factors.[24–26]. Here, CD82 is linked to Familial prostate cancer.