ATF5 and hepatocellular carcinoma: Because none of the commercial antibodies tested showed specific signals against endogenous or exogenous Atf5 protein, we constructed expression vectors for mouse Atf5 with 1 copy of the HA tag at the C-terminus and established Hepa1–6 cells (a mouse hepatoma cell line) stably expressing the HA-tagged Atf5 (Hepa-Atf5) or the control vector (Hepa-Ctl).