Regulation of Plasminogen Activator Synthesis in Chick Embryo Fibroblasts Infected with Avian Retroviruses

The synthesis of the protease plasminogen activator (PA) has been shown to correlate with the transformation of a variety of fibroblasts by both RNA and DNA tumor viruses (Ossowski et al. 1973a; Unkeless et al. 1973; Goldberg 1974; Pollack et al. 1974; Christman and Acs 1974). This includes both avian and murine retroviruses, as well as the papovaviruses, SV40, and polyoma virus. In SV40 transformation, PA induction has been shown to correlate with the production of a normal-size small T protein (Frisque et al. this volume), whereas, in polyoma virus transformation, PA induction is dependent on the synthesis of normal middle T protein (Griffin et al. this volume).