(A) Semi-quantitative RT-PCR showing the relative expression levels of total FOXM1 mRNA in normal oral mucosa (NOM; #1–2), moderate dysplasia (MD; #3–4), severe dysplasia (SD; #5–6), primary HNSCC (#7–8), premalignant oral keratinocytes SVpgC2a, HNSCC cell lines SqCC/Y1 and SCC25. POLR2A was used as an endogenous reference gene. (B) Bioinformatics analysis of microarray data performed on primary cells extracted from normal oral mucosa (NOM), leukoplakia, erythroplakia and primary HNSCC with sample number as indicated. Statistically significant (***P<0.001) activation of FOXM1 mRNA levels when compared to NOM. (C) Quantitative real-time RT-PCR showing relative fold change in FOXM1 mRNA expression levels in HNSCC-derived keratinocytes (n = 15) compared to normal oral mucosa keratinocytes (NOK; n = 4). (D–I) Immunohistochemistry of FOXM1 protein on a panel of FFPE normal oral mucosa (D), mild/moderate dysplasia (E), moderate/severe dysplasia (F), severe dysplasia/carcinoma in situ (G), primary HNSCC (H) and lymph node HNSCC metastasis (I). (J) Digital pixel densitometry for FOXM1 protein immunoreactivity in a panel of 25 oral tissues (n = 5 in each group) as shown in D–I. **(P<0.01) and ***(P<0.001) indicate statistically significant elevation of FOXM1 protein levels when compared to NOM tissues.