GAD-positive cells do not exhibit Kv2.1 expression in the AIS. DIV14 hippocampal neurons were fixed and stained for endogenous Kv2.1 and glutamic acid decarboxylase (GAD) to identify inhibitory neurons. The orange arrows indicate the GAD-negative neurons while the white arrowhead points to a GAD-positive cell. The white arrows indicate the AIS-localized Kv2.1 associated with the GAD-negative neurons. These results are consistent with Kv2.1 localization to the AIS only in excitatory, GAD-negative pyramidal neurons.