Figure 1.

Time- and dose-dependent induction of neurites in PC12 cells expressing chimeric receptors: PFR1 (A); PFR3, (B); and PFR4 (C). Cells, plated as described in Materials and Methods, were treated with various concentrations of PDGF (1, 10, and 30 ng/ml) for 4, 8, 24, 48, and 96 hr, as indicated, and scored for the presence of neurites. After 48 and 72 hr (also 24 hr for PFR4), the medium was changed, and fresh PDGF was added to the cells. In the case of PFR1, the 24-hr time point could not be included because most of the cells expressing this chimera lifted in the presence of PDGF. However, they subsequently reattached to the cell culture plates and presented neurites comparable to the other cell lines at the longer time points. Values are the average of duplicate determinations from a representative experiment.