An Endothelial Cell Growth Factor from the Mouse Neuroblastoma Cell Line NB41

A growth factor that stimulates the proliferation of endothelial cells from human umbilical vein but is not mitogenic for fibroblastic cells is present in medium conditioned by the mouse neuroblastoma cell line NB41. In a partially purified preparation, factor activity coeluted from a reverse-phase high-pressure liquid chromatography (HPLC) column with a reduced protein of about 24 kd. Activity recovered following electrophoresis of HPLC fractions corresponded to protein of 43-51 kd in the absence of reducing agent and to protein of 23-29 kd after reduction. Antiserum raised against a peptide corresponding to the putative N-terminal amino acid sequence of the 24-kd protein reacted with the 24-kd protein and with a protein of about 47 kd in the nonreduced preparation. After N-glycanase treatment, the immunoreactive 24-kd protein had a mobility corresponding to 19 kd. We infer that the native NB41 factor is a glycosylated dimer whose biochemical and biological properties distinguish if from other endothelial cell growth factors.