Figure 4.
Loss of Hzf does not affect the transcription or protein stability of C/EBPα. (A) 3T3-L1 cells infected with the indicated retroviruses were cultured in normal or differentiation-inducing media for 4 days. Expression of C/EBPα, C/EBPβ, and C/EBPδ mRNA was analysed by real-time quantitative PCR. Values were normalized to the expression of GAPDH mRNA. (B) 3T3-L1 cells differentiated for 4 days were treated with 5 μg/ml of actinomycin D for indicated periods, and expression of C/EBPα mRNA was analysed by real-time PCR. Values were normalized to the amount of 18S rRNA in each sample. (C) Cells differentiated (4 days) were pulse-labelled with 35S-Met/Cys for 1 h and chased for the indicated periods. C/EBPα or CDK4 protein was immunoprecipitated, separated on denaturing gels, and detected by autoradiography. Radioactivity in each band was measured (lower panel).