PTEN and colorectal carcinoma: Chiba and the colleagues reported that exosome transfer of miR-21 from SW480 CRC cells promoted the migration ability of HepG2 hepatocellular cancer cells via suppressing their target genes phosphataseand tensin homolog (PTEN) [58]; furthermore, HCC-derived exosomes mediated miRNA transfer has been reported to be an important mechanism of environmental modulation of HCC growth and progression [59].