<unk>  (Simian Vacuolating Virus 40 TAg) is a hexamer protein that is a dominant-acting oncoprotein derived from the polyomavirus<unk> . TAg is capable of inducing malignant transformation of a variety of cell types. The transforming activity of TAg is due in<unk>  part to its perturbation of the retinoblastoma (pRb) and p53 tumor suppressor proteins. In addition, TAg binds to several other cellular factors, including the transcriptional co-activators p300 and CBP, which may contribute to its transformation function. TAg is a product of an early gene transcribed during viral infection by<unk> , and is involved in viral genome replication and regulation of host cell cycle.<unk>  is a double-stranded, circular DNA virus belonging to the Polyomaviridae (earlier Papovavirus) family, Orthopolyomavirus genus. Polyomaviruses infect a wide variety of vertebrates and cause solid tumours at multiple sites.<unk>  was isolated by Sweet and Maurice Hilleman in 1960 in primary monkey kidney cell cultures being used to grow Sabin OPV.
SV40 large T antigen
Adenovirus E1B protein
CccDNA
Long interspersed nuclear element
OTL-103
T independent antigen 
CAd3-ZEBOV
Kaposi's sarcoma-associated herpesvirus