Abstract
Basic calcium phosphate crystals control the traverse of cells from the
Go
G1
to S-phase of the cell cycle and initiate proliferation by rendering fibroblasts competent to respond to insulin-like growth factors in plasma. Simultaneous addition of phosphocitrate [a powerful inhibitor of hydroxyapatite crystallization] to cells exposed to basic calcium phosphate crystals caused a dose-dependent inhibition of crystal-induced DNA synthesis and c-
fos
transcription. This inhibition was specific for crystal-induced mitogenesis, since similar concentrations of phosphocitrate had no effects on either PDGF or 10% calf serum-induced thymidine incorporation and c-
fos
transcription.
