Adapter protein involved in protein degradation by interacting with COP1 ubiquitin ligase (PubMed:23515163, PubMed:20410507). Promotes CEBPA degradation and inhibits its function (PubMed:20410507). Controls macrophage, eosinophil and neutrophil differentiation via the COP1-binding domain (PubMed:24003916, PubMed:23515163). Regulates myeloid cell differentiation by altering the expression of CEBPA in a COP1-dependent manner (PubMed:23515163). Interacts with MAPK kinases and regulates activation of MAP kinases, but has no kinase activity (By similarity). Monomer. Interacts (via protein kinase domain) with CEBPA. Interacts with COP1. The COP1-binding motif (355-360) is required for regulation activity (PubMed:24003916). The C-terminus (351-372) is required for interaction with COP1 (By similarity). The protein kinase active site is incompatible with ATP binding and is inactive (By similarity). Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. Tribbles subfamily.