B 1 ) ▁and ▁e psilon - 4 ▁( AP 4 E 1 ; ▁this ▁gene ), ▁a ▁medium ▁chain , ▁mu - 4 ▁( AP 4 M 1 ), ▁and ▁a ▁small ▁chain , ▁s igma - 4 ▁( AP 4 S 1 ). ▁ ▁C lin ical ▁relev ance ▁▁ ▁It ▁is ▁currently ▁hypoth es ized ▁that ▁AP 4 - complex - medi ated ▁tra ff ick ing ▁plays ▁a ▁cru cial ▁role ▁in ▁brain ▁development ▁and ▁function ing . ▁ ▁Model ▁organ isms <0x09> <0x09> <0x09> <0x09> ▁ ▁Model ▁organ isms ▁have ▁been ▁used ▁in ▁the ▁study ▁of ▁AP 4 E 1 ▁function . ▁A ▁conditional ▁knock out ▁mouse ▁line , ▁called ▁Ap 4 e 1 tm 1 a ( K O MP ) W t si ▁was ▁generated ▁as ▁part ▁of ▁the ▁International ▁Kno ck out ▁Mouse ▁Cons ort ium ▁program ▁— ▁a ▁high - through put ▁mut agen esis ▁project ▁to ▁generate ▁and ▁dist ribute ▁animal ▁models ▁of ▁disease ▁to ▁interested ▁scient ists . ▁ ▁Male ▁and ▁female ▁animals ▁under w ent ▁a ▁standard ized ▁phen ot yp ic ▁screen ▁to ▁determine ▁the ▁effects ▁of ▁delet ion . ▁Tw enty ▁four ▁tests ▁were ▁carried ▁out ▁on ▁hom o zy g ous ▁mut ant ▁m ice ▁and ▁four ▁significant ▁ab normal ities ▁were ▁observed . ▁Fem ales ▁displayed ▁decre ased ▁vertical ▁activity ▁in ▁an ▁open ▁field ▁test , ▁had ▁an ▁ab normal ▁complete ▁blood ▁count , ▁hy po fer rem ia , ▁and ▁a ▁decre ased ▁cor pus ▁call