Cell-permeable. A potent and selective chemical probe for the methyllysine (Kme) reading function of L3MBTL3, a member of the malignant brain tumor (MBT) family of chromatin-interacting transcriptional repressors. It binds L3MBTL3 with a Kd value of 120 nM (IC₅₀ = 40 nM), competitively displacing mono- or dimethyl-lysine containing peptides. UNC1215 is > 50-fold selective toward L3MBTL3 than other members of the human MBT family and demonstrates selectivity against more than 200 other Kme reader domains examined.