TRPM4 and Familial prostate cancer: In addition, TRPM4 (chr19q), encoding a calcium-activated ion channel, is up-regulated in all clusters except best-prognosis iCluster2, and was recently identified as a driver gene in the progression to androgen-independent prostate cancer (Schinke et al., 2014), possibly via its role in cell proliferation and β-catenin signalling (Armisén et al., 2011).