Sequencing of portions (polymerase, envelope, and part of the 3’ LTR) of the TBLV retroviral genome were recovered by PCR amplification from tumors induced with or without Rem expression. PCR products from the mouse Gapdh gene were obtained as a control for acquisition of mutations during PCR and library preparation. Overall design: PCR products and library preparation from several different parts of the TBLV genome were obtained for sequence analysis to determine if the loss of Rem gave hypermutation typical of Apobec cytidine deaminases.