Requirement for the Large T and Small T Proteins of SV40 in the Maintenance of the Transformed State

The virus-cell interaction that leads cells that are nonpermissive for viral growth to become transformed and ultimately tumorigenic is complex, involving multiple viral stimuli and an array of host responses. The portion of the SV40 genome required for the induction of transformation (Graham et al. 1975) encodes two proteins, large T (m.w. 96,000) and small T (m.w. 17,000) (Prives et al. 1977). In response to these two proteins, cells acquire a variety of properties not demonstrated by their uninfected counterparts. These transformed cells proliferate at higher temperatures (Ossowski and Sachs 1967), frequently grow to much higher population densities, grow in medium supplemented with only low levels of serum factors, and exhibit anchorage-independent growth (Risser and Pollack 1974).