“…Super T-Ag may be generated as a result of internal in-phase duplications in the coding region of the T-Ag gene (20)(21)(22), with the duplicated sequence corresponding to the region of the SV40 genome to which many of the tsA mutations have been mapped (17), or by differential splicing between two integrated partial copies of the viral genome (19). Rearrangements of integrated viral sequences can occur in SV40-transformed cells after the initial integration event (1,2,8,12,14,25,26) or soon after infection, before viral DNA integration (19,24). Some such rearrangements result in the capacity to generate super T-Ag (if a functional SV40 origin of replication is present [9]).…”