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  Introduction: miRs, small molecules with wide impact
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  A role for hypoxia in the regulation of miR expression
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  Role of HIF in the regulation of miR‐210
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  The ongoing search for miR‐210 targets
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  Perspectives: towards clinical applications of miR‐210 manipulation

MicroRNAs (miRs) are short non‐coding transcripts involved in a wide variety of cellular processes. Several recent studies have established a link between hypoxia, a well‐documented component of the tumour microenvironment, and specific miRs. One member of this class, miR‐210, was identified as hypoxia inducible in all the cell types tested, and is overexpressed in most cancer types. Its hypoxic induction is dependent on a functional hypoxia‐inducible factor (HIF), thus extending the transcriptional repertoire of the latter beyond ‘classic’ genes. From a clinical standpoint, miR‐210 overexpression has been associated with adverse prognosis in breast tumours and been detected in serum of lymphoma patients and could serve as a tool to define hypoxic malignancies. We discuss the role of miR‐210 and its emerging targets, as well as possible future directions for clinical applications in oncology and ischaemic disorders.