Embryonic striatal cells were immortalized using the A58 temperature-sensitive allele of the SV40 large T antigen. Two cell lines, M213-2O and M26-1F, with gamma-aminobutyric acid (GABA)ergic properties were selected from 85 clones thus developed. M213-2O is a multipolar, polygonal cell line which expresses SV40 large T antigen and glutamate decarboxylase (GAD) at the permissive temperature (33 degrees C) and GAD and MAP-2 immunoreactivity at the nonpermissive temperature (39.3 degrees C). M26-1F has a fibroblast-like morphology and expresses SV40 large T antigen and GAD both at the permissive and nonpermissive temperatures and MAP-2 immunoreactivity at the nonpermissive temperature. Both lines contain GABA as measured by reversed-phase HPLC and M213-2O expresses nipecotic-sensitive [14C]GABA uptake.