CD9 and prostate cancer: Research in prostate cancer has revealed seven new cancer-specific gene fusions, two involving the E26 transformation-specific or E-twenty-six transcription factor family (ETS) genes, ETS translocation variant 1 (ETV1) and ETS related gene (ERG), and four involving non-ETS genes such as CDKN1A (p21), cell surface glycoprotein encoded by CD9 gene (CD9), and IKBKB (IκK-beta) [48].