In breast cancer, GAS5 participates in the activation of proteins that include PTEN, PDCD4, DKK2, FOXO1, and SUFU through a ceRNA mechanism mediated by various miRNAs, including miR-21, miR-222, miR-221-3p, miR-196a-5p, and miR-378a-5p. This evidence concerns the gene PTEN and breast cancer.