▁e . g . ▁in ▁breast ▁and ▁pro state ▁cancer , ▁the ▁t issue ▁structure ▁in ▁distant ▁met ast atic ▁fo ci ▁is ▁similar ▁to ▁the ▁primary ▁tum or ▁structure . ▁According ▁to ▁Fried l ▁and ▁Gil m our , ▁several ▁assumptions ▁can ▁be ▁made ▁based ▁on ▁these ▁data . ▁First , ▁invasion ▁and ▁met ast asis ▁can ▁occur ▁without ▁E MT . ▁Second , ▁detection ▁of ▁single ▁dis sem in ated ▁cells ▁during ▁a ▁routine ▁path olog ic ▁exam ination ▁of ▁tum or ▁t issue ▁samples ▁seems ▁to ▁be ▁a ▁rather ▁complex ▁task , ▁and ▁identification ▁of ▁these ▁cells ▁during ▁E MT ▁is ▁actually ▁impossible . ▁And , ▁third , ▁tum or ▁cells ▁tempor arily ▁use ▁the ▁E MT ▁mechan isms ▁for ▁int ra vas ation ▁and ▁spread ▁to ▁distant ▁org ans ▁and ▁t issues , ▁where ▁they ▁return ▁to ▁the ▁ep ith el ial ▁phen ot ype . ▁This ▁transformation ▁is ▁described ▁as ▁the ▁mes en ch ym al - ep ith el ial ▁transition ▁( ME T ). ▁M ET ▁has ▁been ▁induced ▁experiment ally , ▁and ▁individually ▁moving ▁cells ▁formed ▁mult ic ell ular ▁complex es , ▁but ▁the ▁mole cular ▁mechan isms ▁of ▁M ET ▁under ▁phys i ological ▁conditions ▁remain ▁unknown . ▁N gu yen ▁et ▁al . ▁demonstrated ▁that ▁the ▁select ive ▁in hib itor ▁P D 1 7 3 0 7 4 ▁of ▁the ▁fib ro blast ▁growth ▁factor ▁re ceptor ▁ 1 ▁( F G FR 1 ) ▁in hib its ▁the ▁M AP