[The role of region pX in the life cycle of HTLV-I and in carcinogenesis].

The review considers the molecular biological organization of genome region pX of the human T-cell leukemia virus type I (HTLV-I) along with the structure and functions of regulatory proteins Tax, Rex, and poorly studied Rof and Tof. Tax functions are described, including transcriptional trans-activation, trans-repression, and effects on apoptosis and the cell cycle. The roles of Tax and Rex in controlling gene expression and replication of HTLV-I are discussed.