CHRNA7 and pheochromocytoma: PC12 (rat pheochromocytoma) and SH-SY5Y (human neuroblastoma) cells express endogenous α7nAChR on the cell surface; the dissociation constant (KD) value of [125I]-α-bungarotoxin binding to endogenous α7nAChRs in untransfected SH-SY5Y cells is 0.6 ± 0.3 nM [11].