▁formation ▁of ▁l ym ph atic ▁vessels ▁without ▁alter ing ▁ang i ogen esis , ▁while ▁M MP - 2 ▁in hib ition ▁slow ed ▁the ▁migration ▁of ▁l ym ph atic ▁end oth el ial ▁cells ▁and ▁alter ed ▁the ▁morph ology ▁of ▁new ▁vessels . ▁These ▁results ▁suggest ▁that ▁M MP - 2 ▁may ▁alter ▁tum or ▁vi ability ▁and ▁invasion ▁by ▁reg ulating ▁l ym ph ang i ogen esis ▁in ▁addition ▁to ▁ang i ogen esis . ▁ ▁In hib ition ▁of ▁M MP - 2 ▁as ▁cancer ▁ther apy ▁ ▁C lin ical ▁tri als ▁for ▁cancer ▁ther ap ies ▁using ▁M MP ▁in hib itors ▁have ▁yield ed ▁generally ▁un success ful ▁results . ▁These ▁poor ▁results ▁are ▁likely ▁due ▁to ▁the ▁fact ▁that ▁M MP s ▁play ▁complex ▁roles ▁in ▁t issue ▁formation ▁and ▁cancer ▁pro gression , ▁and ▁indeed ▁many ▁M MP s ▁have ▁both ▁pro ▁and ▁anti - t um or ogen ic ▁properties . ▁Furthermore , ▁most ▁clin ical ▁studies ▁involve ▁advanced ▁stages ▁of ▁cancer , ▁where ▁M MP ▁in hib itors ▁are ▁not ▁particularly ▁effective . ▁Finally , ▁there ▁are ▁no ▁reliable ▁bi om ark ers ▁available ▁for ▁assess ing ▁the ▁effic acy ▁of ▁M MP ▁in hib itors ▁and ▁M MP s ▁are ▁not ▁directly ▁c yt ot ox ic ▁( so ▁they ▁do ▁not ▁cause ▁tum or ▁shr ink age ), ▁so ▁it ▁is ▁difficult ▁for ▁research ers ▁to ▁determine ▁whether ▁the ▁in hib itors ▁have ▁successfully ▁reached ▁their ▁targets