PDCD4 and head and neck squamous cell carcinoma: In addition, after a re-analysis of The Cancer Genomic Atlas head and neck squamous cell carcinoma (TCGA-HNSCC) (n = 497) (https://www.cancer.gov/tcga), we demonstrated elevated miR-21-5p levels in patients with HNSCC, and this was inversely correlated with expression of the PDCD4 tumor suppressor (Figure 2B).