PTPRD and glioblastoma: Subsequent studies reported homozygous deletions of PTPRD in a broad spectrum of human tumor types, such as lung adenocarcinoma [9], [12], [22], [23], pancreatic carcinoma [24], melanoma [25] and glioblastoma [5], etc. Kohno et al. observed reduced PTPRD expression in the majority (>80%) of cell lines and surgical specimens of lung cancer [14].