The Trib3 C-terminus can functionally replace the Trib1 C-terminus. (A) Schematic of C-terminal domain swap mutants. *The COP1 binding site DQXVP. (B) Western blot for protein expression of indicated domain swap mutants in transfected 293T cells. The expressed proteins were detected with an anti-myc antibody (9E10) and are indicated with arrows. β-Actin was the protein loading control. (C) Western blot for C/EBPα in sorted 32D cells transduced with the indicated retrovirus. Endogenous C/EBPα expression was detected with an anti-C/EBPα antibody. β-Actin served as the protein loading control. (D) Flow cytometric analysis for CD11b in 32D cells transduced with indicated retrovirus, then plated in IL-3 or G-CSF for 3 days. Data are representative of 3 independent experiments.