– 1 6 8 1 ▁Category : English ▁MP s ▁ 1 6 8 1 <0x0A> </s> ▁Down ▁Inc ogn ito ▁is ▁a ▁song ▁by ▁W inger , ▁released ▁as ▁a ▁single ▁in ▁ 1 9 9 3 , ▁from ▁their ▁album ▁P ull . ▁Re leased ▁in ▁ 1 9 9 3 , ▁it ▁reached ▁# 1 5 ▁on ▁the ▁Main stream ▁rock ▁Billboard ▁charts . ▁ ▁Category : W inger ▁( band ) ▁songs ▁Category : 1 9 9 3 ▁singles ▁Category : S ongs ▁written ▁by ▁K ip ▁W inger ▁Category : 1 9 9 3 ▁songs ▁Category : At l antic ▁Records ▁singles <0x0A> </s> ▁Pit rak in ra ▁( tra de ▁name ▁Aer ov ant ) ▁is ▁a ▁ 1 5 - k Da ▁human ▁recom bin ant ▁protein ▁of ▁wild - type ▁human ▁inter le uk in - 4 ▁( IL - 4 ). ▁It ▁is ▁an ▁IL - 4 ▁and ▁IL - 1 3 ▁ant agon ist ▁that ▁has ▁been ▁studied ▁in ▁a ▁phase ▁II b ▁clin ical ▁trial ▁for ▁the ▁treatment ▁of ▁ast h ma . ▁Two ▁point ▁mut ations ▁on ▁pit rak in ra ▁( position ▁ 1 2 1 ▁mut ated ▁from ▁arg in ine ▁to ▁as part ic ▁acid ▁and ▁position ▁ 1 2 4 ▁mut ated ▁from ▁ty ros ine ▁to ▁as part ic ▁acid ) ▁confer ▁its ▁ability ▁to ▁block ▁signal ing ▁of ▁IL - 4 ▁and ▁inter le uk in - 1 3 ▁( IL - 1 3 )