Of note, the authors of two recent studies have reported that under hypoxic conditions, tumor cells can release exosomes enriched in miR-21 and matrix metalloproteinase-13 (MMP-13), which lead to an increase in vimentin and decrease in E-cadherin in normoxic cells, thus enhancing metastases occurring via EMT [31, 32]. This evidence concerns the gene MMP13 and neoplasm.