Effects of acetaldehyde-generating system (AGS) on interferon-γ (IFNγ)-induced surface major histocompatibility complex I (MHC class I) levels and signal transducer and activator of transcription 1 (STAT1) signaling. A and B: HepG2.2.15 cells were treated or not with AGS for 72 h in the presence of IFNγ. Then, surface MHC class I were removed from cell surface by low acid wash, followed by measuring restoration of human MHC class I by flow cytometry using anti-human leukocyte antigen-A2 (HLA-A2) antibody. Mouse IgG2b K isotype control (allophycocyanin, APC) was used. C and D: HepG2.2.15 cells were treated or not with AGS for 72 h and with IFNγ for the last 1 h, and STAT1 phosphorylation (pSTAT1) was measured. Total STAT1 was used to normalize the data, and β-actin was also used as internal control. Data are from 3 independent experiments presented as means ± SE. Bars marked with the same lowercase letter are not significantly different from each other; bars with different lowercase letters are significantly different (P ≤ 0 0.05).