PIK3R1（phosphoinositide-3-kinase regulatory subunit 1），癌症关联基因，基因ID：5295，磷脂酰肌醇3-激酶在3-主要位置磷酸化磷脂酰肌醇的肌醇环。所述酶包括110 kD催化亚单位和85、55或50 kD调节亚单位。该基因编码85kD调节亚单位。磷脂酰肌醇3激酶在胰岛素的代谢作用中起着重要作用，该基因的突变与胰岛素抵抗有关。这种基因的选择性剪接导致四个转录变体编码不同的亚型。Phosphatidylinositol 3-kinase phosphorylates the inositol ring of phosphatidylinositol at the 3-prime position. The enzyme comprises a 110 kD catalytic subunit and a regulatory subunit of either 85， 55， or 50 kD. This gene encodes the 85 kD regulatory subunit. Phosphatidylinositol 3-kinase plays an important role in the metabolic actions of insulin， and a mutation in this gene has been associated with insulin resistance. Alternative splicing of this gene results in four transcript variants encoding different isoforms.关联癌症：乳腺癌，多形性胶质母细胞瘤。关联化疗药物：Buparlisib，Torkinib。