Fig. 1

Lkb1 ablation alone induces LSCC development with negative JNK1/2 activities. a Upper panel: Gross appearance of lung tumors in 13-month-old (13M) CCSP^iCreLkb1^f/f (Lkb1^d/d) mice. SCC squamous cell carcinoma; SCC was labeled by a dash cycle and an arrow (upper panel). Scale bar: 0.5 cm. Lower panel: Representative 13M Lkb1^d/d mouse lung SCC (H&E). Infiltrates of neutrophils were commonly associated with SCC nests (black arrow, lower panel). Keratinization was frequently present in SCCs (blue arrow, lower panel). Scale bar: 60 μm. b Representative immunohistochemistry (IHC) staining of 13M Lkb1^d/d mouse lung SCC. SCC markers: p63 and ΔNp63; AD marker: TTF1. “+” means the expression is mild or moderate, and “++” means the expression is strong. Dashes outline: Regions of interest. Positive staining is indicated in some panels by green arrows. Scale bar: 10 μm. c Alignment of the gene signature of 13-month-old Lkb1^d/d mouse lung SCC tumors with Takeuchi human lung cancer database (GSE11969). A score greater than zero indicates a positive correlation with the murine gene signature of 13-month-old Lkb1^d/d mouse. AD adenocarcinoma, ASC adenosquamous carcinoma, LCC large-cell carcinoma, LCNEC large-cell neuroendocrine carcinoma, SCC squamous cell carcinoma, SCLC small cell lung cancer. ANOVA (Tukey−Kramer Multiple Comparisons (TKMC) Test) was performed and error bar is SEM; *P < 0.05; ***P < 0.001. d Western blot (WB) analysis (n = 5) of protein expression in 13-month-old (13M) mice. e WB analysis (n = 3) of protein expression in 3-month-old (3M) mice. f Gene set enrichment analysis (GSEA) of pre-ranked genes detected in microarrays analysis of 13-month-old Lkb1^d/d mouse lung SCCs. All detected genes (Supplementary Data 3) were ranked based on their fold changes (Lkb1^d/d SCC vs. WT) from high (the left terminal of X-axis) to low (the right terminal of X-axis)