May play a role in cell cycle regulation. Dual specificity phosphatase active toward substrates containing either phosphotyrosine or phosphoserine residues. Dephosphorylates CDK2 at 'Thr-160' in a cyclin-dependent manner (By similarity). H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Interacts with cyclin-dependent kinases such as CDK1, CDK2 and CDK3. Does not interact with CDK4. Interacts (via C-terminus) with phosphorylated CDK2 (via C-terminal helix). Interacts with MS4A3 (via C-terminus); the interaction enhances CDKN3 enzymatic activity (By similarity). Belongs to the protein-tyrosine phosphatase family.