One of the recent discovered Hsp 90 inhibitors is deguelin [15], [29], here we found that deguelin depleted Hsp 90 client proteins including Akt, survivin and Cdk4 by disrupting the their association with Hsp 90, all these proteins are proven to be important for cancer development for HNSCC [12], [45], [46]. Here, CDK4 is linked to head and neck squamous cell carcinoma.