4 4 - year - old ▁C au cas ian ▁female , ▁HT - 2 9 ▁cells ▁form ▁a ▁tight ▁mon ol ayer ▁while ▁exhib iting ▁similarity ▁to ▁enter ocy tes ▁from ▁the ▁small ▁int est ine . ▁HT - 2 9 ▁cells ▁over produ ce ▁the ▁p 5 3 ▁tum or ▁ant igen , ▁but ▁have ▁a ▁mut ation ▁in ▁the ▁p 5 3 ▁gene ▁at ▁position ▁ 2 7 3 , ▁resulting ▁in ▁a ▁hist id ine ▁replacing ▁an ▁arg in ine . ▁The ▁cells ▁pro l ifer ate ▁rapidly ▁in ▁media ▁containing ▁sur amin , ▁with ▁corresponding ▁high ▁expression ▁of ▁the ▁c - my c ▁on c ogene . ▁However , ▁c - my c ▁is ▁der eg ulated , ▁but ▁may ▁have ▁a ▁relation ▁with ▁the ▁growth ▁factor ▁requirements ▁of ▁HT - 2 9 ▁cells . ▁ ▁App lications ▁In ▁pre cl in ical ▁research , ▁HT - 2 9 ▁cells ▁have ▁been ▁studied ▁for ▁their ▁ability ▁to ▁differenti ate ▁and ▁thus ▁simulate ▁real ▁colon ▁t issue ▁in ▁vit ro , ▁a ▁characteristic ▁that ▁has ▁made ▁HT - 2 9 ▁useful ▁for ▁ep ith el ial ▁cell ▁research . ▁The ▁cells ▁can ▁also ▁be ▁tested ▁in ▁v ivo ▁via ▁x en og raft s ▁with ▁rod ents . ▁HT - 2 9 ▁cells ▁termin ally ▁differenti ate ▁into ▁enter ocy tes ▁with ▁the ▁replacement ▁of ▁gl uc ose ▁by ▁gal act ose ▁in ▁cell ▁culture , ▁and ▁with ▁the ▁addition ▁of ▁but yr ate ▁or ▁ac ids , ▁the