▁include ▁a ▁diverse ▁array ▁of ▁ant io x id ant ▁systems ▁to ▁co pe ▁with ▁the ▁radical s ▁generated ▁by ▁the ▁ster oid ogen ic ▁en zym es . ▁ ▁Reg ulation ▁▁ ▁In ▁each ▁ster oid ogen ic ▁cell , ▁the ▁expression ▁of ▁the ▁P 4 5 0 s cc ▁system ▁prote ins ▁is ▁reg ulated ▁by ▁the ▁tro ph ic ▁h orm onal ▁system ▁specific ▁for ▁the ▁cell ▁type . ▁In ▁ad ren al ▁cor tex ▁cells ▁from ▁zona ▁fasc icul ata , ▁the ▁expression ▁of ▁the ▁m R N As ▁encoding ▁all ▁three ▁P 4 5 0 s cc ▁prote ins ▁is ▁induced ▁by ▁cort ic otrop in ▁( ACT H ). ▁The ▁tro ph ic ▁h orm ones ▁increase ▁C Y P 1 1 A 1 ▁gene ▁expression ▁through ▁trans cription ▁factors ▁such ▁as ▁ster oid ogen ic ▁factor ▁ 1 ▁( SF - 1 ), ▁by ▁the ▁α ▁is o form ▁of ▁activ ating ▁protein ▁ 2 ▁( AP - 2 ) ▁in ▁the ▁human , ▁and ▁many ▁others . ▁The ▁production ▁of ▁this ▁en zym e ▁is ▁in hib ited ▁not ably ▁by ▁the ▁nuclear ▁re ceptor ▁D AX - 1 . ▁ ▁P 4 5 0 s cc ▁is ▁always ▁active , ▁however ▁its ▁activity ▁is ▁limited ▁by ▁the ▁supply ▁of ▁ch ol ester ol ▁in ▁the ▁inner ▁memb rane . ▁ ▁The ▁supp lying ▁of ▁ch ol ester ol ▁to ▁this ▁memb rane ▁( from ▁the ▁outer ▁mit och ond rial ▁memb rane ) ▁is