ST14 and prostate cancer: Tmprss2 has been shown to be inhibited by hepatocyte-activating inhibitor-2 (HAI-2) (Faller et al, 2014) and reported to activate the transmembrane serine protease matriptase (St14) to promote extracellular matrix degradation, prostate cancer cell invasion, tumour growth, and metastasis via overactivation of MET, the specific receptor of hepatocyte growth factor (Ko et al, 2015; Mukai et al, 2020).