Results from our gene expression profiling study are in broad agreement with previous studies performed on non-small-cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC), where greater than 95% of cases have been shown to overexpress BMP2, phosphorylated SMAD1/5, and Id1 [48,66]. This evidence concerns the gene SMAD1 and head and neck squamous cell carcinoma.