PCNA and acute liver failure: In the second model in which C57/B6 mice were injected with a single dose of acetaminophen (APAP) to induce acute liver failure, similar observations were made that Trib1 expression was down-regulated at 1d and 2d in the liver after APAP injection, which mirrored PCNA/cyclin D1/CDK4 up-regulation (Fig. 1D–F).