For example, EVs secreted by hypoxic pre-stimulated MSCs delivered miR-21-5p into NSCLC cells, which not only accelerated tumor growth in vivo but also facilitated intratumoral angiogenesis and macrophage M2 polarization by decreasing the expression of PTEN, PDCD4 and RECK genes in NSCLC cells (Ren et al., 2019). Here, RECK is linked to non-small cell lung carcinoma.