OGFR and lung cancer: MENK has been shown to change EMT markers expression towards a less invasive phenotype, including downregulation of MMP2 in human lung cancer A549 and H1975 cells via interaction with OGFR, followed by migration inhibition, while knockdown of OGFR and exposure to MENK resulted in a reversed EMT marker expression pattern, possibly through an alternative, classical opioid receptor-mediated pathways [45], (Table 2).