RGB-286638 is a multi-target CDK inhibitor that effectively hampers the kinase activity of a range of cyclin-CDK complexes, including cyclin T1-CDK9 (IC50 = 1 nM), cyclin B1-CDK1 (IC50 = 2 nM), cyclin E-CDK2 (IC50 = 3 nM), cyclin D1-CDK4 (IC50 = 4 nM), cyclin E-CDK3 (IC50 = 5 nM), and p35-CDK5 (IC50 = 5 nM). Additionally, it inhibits other kinases such as GSK-3β (IC50 = 3 nM), TAK1 (IC50 = 5 nM), Jak2 (IC50 = 50 nM), and MEK1 (IC50 = 54 nM), showcasing its versatile inhibitory potential.