However, expression of a C/EBP-β phospho-acceptor site mutant, C/EBPβT217A, in Cebpb−/− MEFs did not increase SerpinB2 proximal promoter activity over that of wild-type C/EBP-β, even though recruitment of C/EBP-βT217 to the SerpinB2 promoter was observed to decrease following LPS stimulation of RAW264.7 cells.