Expressed in only a subset of distal body wall muscles(BWM) and therefore enables the clear visualization of individual muscle arms. Expression of Mb::YFP from
him-4p in first larval-stage (L1) larvae was limited to four distal BMWs posterior to the neck muscles in each quadrant. As development continued, two more distal BWMs posterior to the initial four in each quadrant also expressed Mb::YFP, albeit at lower levels.