GAS5 and breast cancer: Studies in breast cancer cell lines and murine models have revealed that microRNA-mediated regulation also plays a significant role, as exemplified by miR-21, which directly binds to exon 4 of GAS5, leading to recruitment of the RNA-induced silencing complex (RISC) and subsequent post-transcriptional downregulation of GAS5, forming a mutually negative regulatory feedback loop [42].