RB1 and neoplasm: MiR-106b, miR-32, and miR-221 downregulate PTEN, TP53, and RB1 and increase the probability of tumor cell mutation (Mercatelli et al., 2008; Garofalo et al., 2009; Cai et al., 2011; Kumar et al., 2011; Lupini et al., 2013).