FGF-2 induced proliferation of F32 cells on fixed MAPCs. F32 cells were cultured for 24 hours on fixed monolayers of normal and Hurler MAPCs in the presence of the indicated concentrations of FGF-2. The numbers of cells present in each well were determined as detailed in “Materials and methods.” Cell numbers are expressed as a ratio (number of cells in wells supplemented with FGF-2/number of cells in absence of FGF-2). Proliferation of F32 cells plated on heparitinase I and III (hep'ase)–treated normal and Hurler MAPCs was also examined in parallel wells. n = 2 independent experiments with replicates. ○ indicates Normal MAPC; •, Hurler MAPC; □, No cell layer; ▴, Hep'ase treated Hurler MAPC; and ▵, Hep'ase treated normal MAPC.