Targeting HER2 blunted bleomycin-induced murine lung fibrosis. (A and B) Fibroblast invasion (A) and invasion index (B) after combined treatment of Lapatinib and α-PDL1 (n = 3 per group). (C and D) Masson’s trichrome staining (C) and hydroxyproline content of lung tissues (D) from C57BL/6J mice injured with 1.25 U bleomycin and treated with Lapatinib or vehicle control. Dash-boxed regions were shown at higher magnification (control [CTL] with vehicle, n = 9; CTL with Lapatinib, n = 8; bleomycin with vehicle, n = 9; bleomycin with Lapatinib, n = 7). Three independent experiments were performed on fibroblasts from different patients (B and D). Data are the mean ± SEM. Scale bar: 1 mm (A) and 500 μm (C). *, P < 0.05; **, P < 0.01; ***, P < 0.001; and ****, P < 0.0001 by two-way ANOVA (B and D).