The suppressive function of miR-138 was found to target enhancer of zeste homolog 2 (EZH2) (Zhang et al., 2013; Si et al., 2017), pyruvate dehydrogenase kinase 1 and G protein-coupled receptor 124 (GPR124) (Gao et al., 2014; Ye et al., 2015), SP1 (Liu et al., 2018), SOX9 (Hu et al., 2017), and cyclin D3 (Huang et al., 2015) to inhibit tumor cell growth and migration. The gene discussed is CCND3; the disease is neoplasm.