To further confirm the overexpression of EN2 in PC, we detected the expression of four well-studied biomarker proteins, mTOR (mechanistic target of rapamycin kinase), VEGF (vascular endothelial growth factor), EGFR (epidermal growth factor receptor) and PTEN(gene of phosphate and tension homology deleted on chromsome ten), together with EN2 in these 25 PC and 25 BPH tissues, at mRNA level through real-time PCR. The gene discussed is PTEN; the disease is pachyonychia congenita.