At the time of writing this review, we found five studies on BC reporting that GAS5 acts as a ceRNA for four miRNAs with oncogenic functions (onco-miRs), including miR-21-5p, miR-221-3p, miR-196a-5p, and miR-378-5p [36,37,49,50], and the tumor-suppressor miR-216b [51]. The gene discussed is GAS5; the disease is breast cancer.