PDCD4 and neoplasm: MiR-21 exerts its effect potentially by targeting and inhibiting several tumor suppressor genes, including transforming growth factor beta receptor 2 (TGFβR2) [79], phosphatase and TENsin homolog (PTEN) [80], the translational inhibitor programmed cell death-4 (PDCD4) [81], and the membrane-anchored protease-regulator reversion-inducing cysteine-rich protein with kazal motifs (RECK) [82], thus supporting PCa promotion and progression.