Additionally, the immunofluorescence staining images of two cancer cell lines (human epidermoid carcinoma cell line A-431 and malignant human glioma cell lines U-251) obtained from the HPA database showed that PTPN1 was mainly localized in the endoplasmic reticulum (ER) (Figure 1C). The gene discussed is PTPN1; the disease is squamous cell carcinoma.