We have previously shown that proliferating lymphoblastoid cells, as well as mitogen-stimulated normal lymphocytes, contain cytoplasmic factor(s) which are capable of inducing DNA synthesis in isolated quiescent nuclei. These factors are protein in nature, and are not detectable in the cytoplasm of resting cells. The purpose of this research is to characterize and compare the molecular, physicochemical, and functional properties of such cytoplasmic stimulatory factors extracted from normal and neoplastic cells. Specifically, we will isolate and characterize such factors from a variety of neoplastic cell lines and from lectin and mitogenic hormone-activated normal cells by physicochemical and immunologic techniques. In addition, we will investigate the mechanism of action of these intracellular factors, as well as the control mechanisms which regulate their presence and/or activity. Finally, we will attempt to activate normal intact cells by the intracellular delivery of the nuclear activating factor obtained from normal and neoplastic cells. These studies should provide information on intracellular growth-regulatory mechanisms in normal and noeplastic cells.