CDKL5/GSK3-IN-1 (Compound 2) is a potent and selectivity chemical probe for CDKL5/GSK3.CDKL5/GSK3-IN-1 has potent inhibition of CDKL5 and GSK3α/β , with IC 50 values of 4.6, 24 and 9.5 nM for CDKL5, GSK3β and GSK3α, respectively, in the NanoBRET assay. CDKL5/GSK3-IN-1 can be used for the research of CNS diseases.