Fig. 1.

Expression of activating transcription factor (ATF)3 in HepG2 hepatocellular carcinoma cells after activation of the amino acid response (AAR). A: the hnRNA content of ATF3 was analyzed by qPCR to estimate the transcription activity in HepG2 human hepatocellular cells incubated in control medium (DMEM) or medium containing 2 mM HisOH for 0–24 h. GAPDH mRNA, which is unchanged by the AAR, was used as the internal control. The results are the averages ± SD of 3 or more assays and where not shown, the SD bars are contained within the symbol. B: the steady-state mRNA content of ATF3 was analyzed by qPCR. C: after the cells were treated with HisOH as described above, a 40 μg aliquot of whole cell extract was subjected to gel electrophoresis, transferred to nitrocellulose paper, and then immunoblotted with primary antibody against ATF3 or actin.