1934, vitamin B6 was discovered by P. György. Vitamin B6 consists of 3 closely related pyrimidine derivatives: pyridoxine, pyridoxal and pyridoxamine and their phosphate esters. The tumor-specific compound has been recently found to be as a new B6 derivatives. The active form of vitamin B6 is pyridoxal phosphate (PLP) which is produced by multi-metabolizing enzymes including pyridoxine kinase and PNP/PMP oxidase. PLP functions as the coenzymes of many enzymes which catalyze biochemical reactions such as transamination and decarboxylation. A novel physiological function of PLP which is the negative modulator of the steroid-dependent gene expression and the albumin gene expression has been also revealed.