The gene MAT2β, encodes for a β regulatory subunit that regulates the activity of MATII by lowering inhibition constant (Ki) for SAMe and Michaeli's constant (Km) for methionine [1], MAT2A and its gene product also predominate in the fetal liver and are progressively replaced by MAT1A during development in normal adult liver [31,32] but in liver cirrhosis and cancer, expressions of MAT2A and MAT2β are both increased. The gene discussed is MAT2A; the disease is cancer.