RETrace methylation analysis of U87MG and brain single cells. (A) Pairwise dissimilarity between each U87MG ex vivo single cells and ENCODE reference cell line data. (B) Comparison of RETrace-processed cortical neuronal and nonneuronal nuclei and previously published excitatory and inhibitory neuronal subtypes accurately separate NeuN⁺ and NeuN⁻ nuclei. (C) Similar separation between neuronal and nonneuronal nuclei when analyzing the whole RETrace brain data set.