Plexins expression in leukemic cells. (A) Total RNA (50 ng/μL) was isolated from the indicated cells, and real-time PCR was done with primers and probes specific for plexin-A1, -A2, -A3, and -A4 or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA. Plexin mRNA expression was normalized to GAPDH for each sample. (B) Total lysates (50 μg) from indicated cell lines were immunoblotted (Blot Ab) with antiplexin-A1 antibody. Expression of actin was used as loading control. (C,D) Colocalization of Fas (green) with either plexin-A1 (C) or NP1 (D) (red) in Sema3A-treated Jurkat cells in contrast to cells treated with control IgG (original magnification, ×1600).