EGFR and head and neck squamous cell carcinoma: In the case of the epidermal growth factor receptor (EGFR), EGCG inhibits its activation in carcinoma cells, especially in breast cancer and head and neck squamous cell carcinoma, in which activation of EGFR is essential for tumor survival and growth [13]; therefore, the mechanism of the EGCG anti-cancer effect is based on the suppression of the EGFR signaling pathway, involving a decrease of Akt and ERK1/2 activation (Figure 3).