This extract was created in the absence of an abstract.
Excerpt
Growth factors are implicated in a wide variety of physiological and pathological processes, including embryogenesis, hematopoiesis, wound healing, immune responses, atherosclerosis, and neoplasis (Evered et al. 1985; Sporn and Roberts 1986). An important link between growth factors and their receptors and oncogene products has also been established (Heldin and Westermark 1984; Weinstein 1987). Thus, the elucidation of the mechanism of action of growth factors has emerged as one of the fundamental problems in biology and may prove crucial for understanding the unrestrained proliferation of cancer cells.
Many studis of growth factors have used cultured fibroblasts, such as 3T3 cells, as a model system. These cells cease to proliferate when they deplete the medium of its growth-promoting activity. Such quiescent cells can be stimulated to reinitiate DNA synthesis and cell division either by replenishing the medium with fresh serum or by the addition of growth factors or pharmacological agents in serum-free...