Head activator acts as an autocrine growth factor for NH15-CA2 cells in the G2/mitosis transition

The neuropeptide head activator (HA) acts as an autocrine growth factor for the neural cell line NH15-CA2. Cell proliferation is increased in the presence of HA and inhibited by HA peptide-specific antisera. Stimulation of cellular proliferation is visible 2 h after HA application as an increase in cells in mitosis. HA has no direct effect on stimulating DNA synthesis. HA thus functions as a control signal in the G2/mitosis transition and not in the G1/S transition. Receptors for HA are present on small round cells in clusters of foci and not on cells with differentiated morphology, suggesting cell-cycle-dependent HA receptor expression.