Immunohistochemistry confirmed the same group segregation as was determined by the methylation analysis: (1) α-like tumours expressed ARX (Fig. 1c, Supplementary Data 1), (2) β-like tumours expressed PDX1, with only one sample positive for ARX and PDX1 negative (Fig. 1c, Supplementary Data 1), (3) 38/44 (86%) intermediate PanNETs were positive for ARX and only two cases were PDX1 positive and ARX negative. The gene discussed is PDX1; the disease is neoplasm.