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 (By similarity). Expressed in liver, kidney, muscle, thymus, and bone marrow. Weakly expressed in spleen. Weakly expressed in embryo compared to VRK1 and VRK3. Expressed from 10.5 dpc to 13.5 dpc in developing liver and then decreases. It increases again from 17.5 dpc and remains thereafter. Highly expressed in hematopoietic embryonic tissues from 10.5 dpc to 14.5 dpc. Strongly expressed in the yolk-sac. 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.