Major motility patterns of gastrointestinal (GI) organs were thought traditionally to be determined mainly by myogenic and neurogenic mechanisms. More recently interstitial cells have been recognized as contributing important regulatory functions in GI motor activity.1 At least 2 types of resident interstitial cells (interstitial cells of Cajal [ICC] and PDGFRα+ cells) lie in close proximity to the terminals of enteric motor neurons. Together with smooth muscle cells, ICC and PDGFRα+ cells form an electrical syncytium (SIP syncytium) and integrate inputs from enteric motor neurons.