approximately 40% of primary human breast cancer tissues have been found to carry the mrna which codes for girk1 subunits. treatment of breast cancer tissue with alcohol has been shown to trigger increased growth of the cancer cells. the mechanism of this activity is still a subject of research. down syndrome altered cardiac regulation is common in adults diagnosed with down syndrome and may be related to g protein-gated ion channels. the kcnj6 gene is located on chromosome 21 and encodes for the girk2 protein subunit of g protein-gated k+ channels. people with down syndrome have three copies of chromosome 21, resulting in an overexpression of the girk2 subunit. studies have found that recombinant mice overexpressing girk2 subunits show altered responses to drugs that activate g protein-gated k+ channels. these altered responses were limited to the sino-atrial node and atria, both areas which contain many g protein-gated k+ channels. such findings could potentially lead to the development of drugs that can help regulate the cardiac sympathetic-parasympathetic imbalance in down syndrome adults. chronic atrial fibrillation atrial fibrillation (abnormal heart rhythm) is associated with shorter action potential duration and believed to be affected by the g protein-gated k+ channel, ik,ach. the ik,ach channel, when activated by g proteins, allows for the flow of k+ across the plasma membrane and out of the cell. this current hyperpolarizes the cell, thus terminating the action potential. it has been shown that in chronic atrial fibrillation there an increase in this inwardly rectifying current because of constantly activated ik,ach channels. increase in the current results in shorter action potential duration experienced in chronic atrial fibrillation and leads to the subsequent fibrillating of the cardiac muscle. blocking ik,ach channel activity could be a therapeutic target in atrial fibrillation and is an area under study. pain management girk channels have been demonstrated in vivo to be involved in opioid- and ethanol-induced analgesia. these specific channels have been the target of recent studies dealing with genetic variance and sensitivity to opioid analgesics due to their role in opioid-induced analgesia. several studies have shown that when opioids are prescribed to treat chronic pain, girk channels are activated by certain gpcrs, namely opioid receptors, which leads to the inhibition of nociceptive transmission, thus functioning in pain relief. furthermore, studies have shown that g proteins, specifically the gi alpha subunit, directly activate girks which were found to participate in propagation of morphine-induced analgesia in inflamed spines of mice. research pertaining to chronic pain management continues to be performed in this field.