Fig. 3. Cells from stromal and tumor compartments of neuroblastoma cells differed in their angiogenic phenotype. (A) Media conditioned by rat Schwann cells or by cultured neuroblastoma tumor cells growing as more differentiated S-type or less differentiated N-type, or by tumor cell line SK-N-BE(2) were assayed for their ability to induce capillary endothelial cell migration. Media were tested alone, or in the presence of an inducer (bFGF was the purified inducer added to the Schwann cell media; VEGF was the purified inducer added the S-type cell media), or in the presence of antibodies to neutralize PEDF or VEGF. The Student’s t test was used to compare data *P<0.009 with that obtained from the corresponding media tested alone. Error bars indicate s.e.m. (B) Controls for the activities of antibodies and proteins were performed by the indicated additions to DMEM/0.1% BSA.