SMAD7 and prostate cancer: A significantly increased expression of HDAC6, Smad7, and c-Jun was observed in prostate cancer tissues with Gleason score ≥8 (including Gleason score 4 + 3) as compared with lower Gleason score ≤6 or 7 (including Gleason score 3 + 4), demonstrating that high expression of these proteins is correlated with prostate cancer progression.