Fig. 6. Interactions between SHH and HSPGs modulate proliferation of more mature granule cells. (A) Proliferation dose response of primary cerebellar cultures from P6 mice to SHH:AP (white squares) or AlaSHH:AP (black diamonds). In this and the following panels, a representative experiment is shown in which data from quadruplicate cultures was averaged and normalized to the mean incorporation observed in the absence of SHH. Values are represented as fold proliferation relative to this control±s.e.m. (B) P6 cultures were treated with SHH in the absence (white squares) or presence (black diamonds) of a mixture of heparinase I and III. In both A and B, P6 cultures display a bell-shaped dose-response to SHH, and disruption of the interaction of SHH and HSPGs reduces the peak proliferative response. (C) Proliferation dose response of primary cerebellar cultures derived from postnatal day 3 (P3) mice to SHH:AP (open squares) or AlaSHH:AP (filled diamonds). (D) P3 cultures were treated with unconjugated SHH in the absence (white squares) or presence (black diamonds) of a mixture of heparinase I and III. In both C,D, P3 cultures display increasing proliferation in response to increasing doses of SHH and disruption of the interaction between SHH and HSPGs has no effect on the proliferative response.