ron ▁General ▁and ▁Children ’ s ▁Hospital ▁of ▁Ak ron ▁in ▁ 1 9 8 8 . ▁In ▁ 1 9 8 9 , ▁Mack all ▁joined ▁the ▁National ▁Can cer ▁Institute ▁as ▁a ▁fellow ▁in ▁Ped iat ric ▁On col ogy , ▁where ▁she ▁began ▁to ▁focus ▁on ▁imm un other apy ▁for ▁cancer .   ▁She ▁remained ▁at ▁National ▁Instit utes ▁of ▁Health ▁until ▁ 2 0 1 6 , ▁eventually ▁serving ▁as ▁the ▁Chief ▁of ▁the ▁Ped iat ric ▁On col ogy ▁Branch .   ▁She ▁moved ▁to ▁the ▁Stan ford ▁University ▁School ▁of ▁Medicine ▁in ▁ 2 0 1 6 .   ▁She ▁is ▁Board ▁Cert ified ▁in ▁In ternal ▁Medicine , ▁Ped iat rics , ▁and ▁Ped iat ric ▁H emat ology / On col ogy . ▁ ▁Research ▁▁ ▁Mack all ▁has ▁pione ered ▁cancer ▁imm un other ap ies ▁for ▁children .   Her ▁early ▁research ▁defined ▁the ▁effects ▁of ▁traditional ▁cancer ▁ther ap ies ▁on ▁the ▁imm une ▁system , ▁where ▁she ▁identified ▁the ▁role ▁of ▁the ▁th ym us ▁in ▁human ▁T ▁cell ▁reg ener ation ▁and ▁discovered ▁that ▁Inter le uk in - 7 ▁( IL - 7 ) ▁is ▁the ▁main ▁reg ulator ▁of ▁T ▁cell ▁home ost asis ▁in ▁humans . ▁Her ▁group ▁was ▁among ▁the ▁first ▁to ▁demonstrate ▁impress ive ▁activity ▁of ▁CD 1 9 ▁ch imer ic ▁ant igen ▁re ceptor ▁( C AR ▁T ▁cells ) ▁ther ap ies ▁for ▁child hood ▁le uk emia ▁and ▁also ▁developed