Heat-Responsive Protein 12 (HRSP12) is an endoribonuclease that belongs to the Rut family. HRSP12 is found mainly in the human adult kidney and liver and is responsible for inhibiting protein translation by cleaving mRNA. HRSP12 only cleaves phosphodiester bonds in single-stranded RNA and inhibits cell-free protein synthesis. The levels of both mRNA and protein are markedly reduced in heptatocellular tumors and in human hepatoma cell lines compared with normal liver tissues. Moreover the levels of HRSP12 are different depending on the grade of the tumor. This had led to the suggestion that HRSP12 may be an important biomarker for heptatic carcinoma.