Another study reported that Survivin overexpressed in the human epidermoid carcinoma cells KBv200 and breast cancer cells MCF-7/Adr did not directly interact with P-gp (Shi et al., 2007), which implied that Survivin might affect the expression and transport activity of P-gp in cancerous cells via other mediator molecules. This evidence concerns the gene PGP and squamous cell carcinoma.