SH-SY5Y is one of three serially isolated neuroblast clones (SH-SY, SH-SY5, SH-SY5Y) of the human neuroblastoma cell line SK-N-SH which was established in 1970 from a metastatic bone tumor. The cells exhibit moderate levels of dopamine beta hydroxylase activity. They can convert glutamate to the neurotransmitter GABA. SH-SY5Y cells have a reported saturation density greater than 1 x 10^6 cells/cm2. The loss of neuronal characteristics has been described with increasing passage numbers (approx. passage 20). Neuronal markers or uptake of noradrenalin should be determined routinely. It is recommended not to use at passage numbers higher than 20 unless neuronal characteristics are controlled.