HIF1A and chronic obstructive pulmonary disease: Some miRNAs are upregulated directly by CSE, like miR-21, which is induced by hypoxia-inducible factor 1-alpha (HIF-1α) (114, 164), or others, like miR-664a-3p (targets FHL1), which is raised in lung tissue and peripheral blood mononuclear cells (PBMCs) from COPD patients, and in Beas-2B cells exposed to CSE (165).