Characterization of Growth Factor-Modulated Events Regulating Cellular Proliferation

This chapter various methods employing requirements for a specific growth factor(s) and essential nutrients are described that can be used to synchronize BALB/c 3T3 cells at the various regulatory points within G₀/G₁. Cells synchronized in this fashion can be used to (1) study the mechanism of action of certain growth factors at the specific cell cycle time when they are required and (2) delineate and order those cellular events required for G₀/G₁ traverse. Traverse of density-arrested fibroblastic cells through G0/GI is mediated by multiple growth factors with sequential or interdependent actions. Platelet-derived growth factor (PDGF) and other known competence factors initiate the proliferative response of BALB/c 3T3 cells and program cells to respond to the progression factors required for G₀/G₁ traverse and entry into S phase.