HSP90AA1 and pancreatic ductal adenocarcinoma: Clinical studies have found that one of the four members of HSP90, HSP90α, is overexpressed in the serum or tissues of many patients with malignant tumors, such as lung cancer (14), prostate cancer (15), pancreatic ductal adenocarcinoma (16), liver cancer (17, 18) and pancreatic cancer (19), etc. Moreover, correlation analysis of some tumor-related clinical studies found that HSP90α was positively related to the metastasis and malignancy (20), and it can be used as a biological marker for diagnosis of tumors (21, 22).