Inactive kinase that suppresses ERK activity by promoting phosphatase activity of DUSP3 which specifically dephosphorylates and inactivates ERK in the nucleus. Interacts with DUSP3. Interacts with RAN. Belongs to the protein kinase superfamily. CK1 Ser/Thr protein kinase family. VRK subfamily. Inactive as a kinase due to its inability to bind ATP.