Despite PRSS3-V2/MTG-mediated oncogenic effects in HCC in line with the promalignant activities of MTG shown in other cancer types (13, 16, 22, 23, 29), PRSS3-V1/TRY-4 or -V3 were found to be tumor suppressors in HCC cells, while ectopic PRSS3-V4 showed an inhibitory effect on PRSS3ko Huh7 cells. The gene discussed is PRSS1; the disease is cancer.