PIK3CD and familial pancreatic carcinoma: Its mutations and abnormal expression were reported to impair PI3K function, and further cause disease.34, 35, 36, 37 An integrative survival‐based molecular profiling of human pancreatic cancer had identified PIK3R1 expression as a putative clinical biomarker for the disease outcome.38 But little was known about the cis‐regulatory element of this gene.