This four-gene model distinguished patient groups at high versus low risk for prostate cancer recurrence by Kaplan–Meier analysis [hazard ratio (HR) = 2.6, P = 0.012]36. In addition, the PTEN/SMAD4/CCND1/SPP1 four-gene signature involves the PTEN and TGFβ pathways, which converges to regulate prostate cancer progression36. Here, SMAD4 is linked to prostate cancer.