Studies have shown that AREG, CTTN, PRKCA, MCL1, PAK4, PLAU and PLK1 are all implicated in OSCC or HNSCC progression and inclined to poor prognosis [40, 41, 48, 51, 55–57], suggesting that these genes may also serve as promising targets for molecular targeted therapy. Here, PLK1 is linked to head and neck squamous cell carcinoma.