PTEN and cancer: Accumulating evidence suggests that miR-21 promotes cell proliferation via PTEN-dependent PI3K/Akt signaling activation in cancer cells (Bai et al., 2011; Di Cristofano & Pandolfi, 2000; Meng et al., 2006; Ou, Li & Kang, 2014; Yan-nan et al., 2014).