MYC mRNA stability may also be enhanced by the hypoxia-induced down-regulation of micro RNAs miR-449a-5p and let-7g, which contribute to hypoxia-induced proliferation of PASMCs in vitro and pulmonary hypertension in vivo (Zhang et al., 2019; Zhang et al., 2017). This evidence concerns the gene MYC and pulmonary arterial hypertension.