▁are ▁the ▁inter medi ary ▁comp ounds ▁and ▁end ▁products ▁of ▁complex ▁bio chem ical ▁re actions ▁that ▁sust ain ▁the ▁cell . ▁Gen et ically ▁identical ▁cells ▁in ▁different ▁conditions ▁and ▁environments ▁can ▁use ▁different ▁met abol ic ▁path ways ▁to ▁sust ain ▁themselves . ▁By ▁meas uring ▁the ▁met abol ites ▁present , ▁scient ists ▁can ▁infer ▁the ▁met abol ic ▁path ways ▁used , ▁and ▁infer ▁useful ▁information ▁about ▁the ▁state ▁of ▁the ▁cell . ▁An ▁example ▁of ▁this ▁is ▁found ▁in ▁the ▁imm une ▁system , ▁where ▁CD 4 + ▁cells ▁can ▁differenti ate ▁into ▁Th 1 7 ▁or ▁T Reg ▁cells ▁( am ong ▁other ▁possibilities ), ▁both ▁of ▁which ▁direct ▁the ▁imm une ▁system ' s ▁response ▁in ▁different ▁ways . ▁Th 1 7 ▁cells ▁stim ulate ▁a ▁strong ▁infl am mat ory ▁response , ▁whereas ▁T Reg ▁cells ▁stim ulate ▁the ▁opposite ▁effect . ▁The ▁former ▁tend ▁to ▁rely ▁much ▁more ▁on ▁g ly col ysis , ▁due ▁to ▁their ▁increased ▁energy ▁dem ands . ▁ ▁In ▁order ▁to ▁profile ▁the ▁met abol ic ▁content ▁of ▁a ▁cell , ▁research ers ▁must ▁identify ▁the ▁cell ▁of ▁interest ▁in ▁the ▁larger ▁population , ▁isol ate ▁it ▁for ▁analysis , ▁quickly ▁in hib it ▁en zym es ▁and ▁halt ▁the ▁met abol ic ▁processes ▁in ▁the ▁cell , ▁and ▁then ▁use ▁techniques ▁such ▁as ▁N MR , ▁mass - spec , ▁micro fl uid ics , ▁and ▁other ▁methods ▁to ▁analyze ▁the ▁contents ▁of ▁the ▁cell . ▁