NCL plays a role in PTN-induced endothelial cell migration. A. Down-regulation of NCL expression by siRNA completely abolished PTN-induced HUVEC migration. B. Blockage of cell surface NCL by its ligand 5(KPR)TASP (TASP, 1 μM) completely abolished PTN-induced HUVEC migration. Results are expressed as percent of the values obtained in untreated cells (control). Data are the mean ± S.E.M. of three independent experiments. Asterisks denote a statistically significant difference from control. *P < 0.05, **P < 0.01. NT, non transfected cells; siNEG, cells transfected with a negative control siRNA; siNCL, cells transfected with siRNA for NCL.