Immunofluorescence (IC) analysis of human neuroblastoma cell line SH-SY5Y (A) and rat pheochromocytoma cell line PC12 (B), using P3345-03, (1:500), in red and costained with chicken pAb to vimentin, (1:10,000) in green. The blue is DAPI staining of nuclear DNA. Peripherin, one of the Class III family of intermediate filament (IF) subunit proteins is revealed by P3345-03 in the perinuclear region in some SH-SY5Y cells and in all PC12 cells. Vimentin, a protein also in the Class III IF family, is detected in a subpopulation of SH-SY5Y cells which are negative for peripherin. PC12 cells express peripherin but not vimentin.