KCNJ5 and breast neoplasm: While GIRK1 has been shown to play an important role in tumorigenesis and progression of breast tumors via irregular overexpression, somatic mutations in KCNJ5, the gene encoding the GIRK4 subunit, have been shown to be important driver mutations for producing sporadic primary aldosteronism, a benign alteration of the adrenal gland resulting in dysregulation of aldosterone production and resulting hypertension (23).