In addition, Kaplan–Meier (KM) survival analysis showed that higher expression of HHLA2 was significantly associated with a poor survival outcome in 62 PC patients (Fig. 3G, p < 0.05).The protein and mRNA expression levels of HHLA2 were detected in normal ductal epithelial cell line of pancreas and different human pancreatic cancer cell lines by WB and RT-qPCR. The gene discussed is HHLA2; the disease is pachyonychia congenita.