¹Schepens Eye Research Institute, 20 Staniford Street, Boston, Massachusetts, MA 02114, USA

²Harvard Medical School, Department of Ophthalmology, Boston, Massachusetts, MA 02115, USA

Correspondence to: A Kazlauskas, Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, Massachussetts, MA 02114, USA

A widely used model system to investigate cell proliferation is stimulation of serum-arrested cells with growth factors. Recent data suggest that there are two waves of growth factor-dependent signaling events required for a proliferative response. One is an acute burst of signaling, which occurs immediately after growth factor stimulation and lasts for 30-60 min. The other occurs in a different time frame (8-12 h post stimulation), and involves activation of cyclin dependent kinases (Cdks). In addition to a general overview of growth factor-dependent signaling, we present our 'two wave' hypothesis for how signaling and cell cycle progression are linked. Oncogene (2000) 19, 5558-5567.

PDGF; cell cycle progression; signal transduction