PTEN and head and neck squamous cell carcinoma: Moreover, six other genes frequently affected in human OSCC, but not found to be altered in the 4MOSC cells, were also mutated in the OSCC13 cells (Pik3cd, Fat1, Notch2, Cdh10, Nf1 and Pten) suggesting that OSCC13 cells phenocopy characteristics described for human HNSCC (Figure 1C).