WordNet (r) 3.0 (2006):

enter upon
    v 1: take possession of; "She entered upon the estate of her
         rich relatives" [syn: enter upon, come upon, luck
         into]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "enter upon":
   accept, assume, attack, attempt, buckle to, come out, dive into,
   embark in, embark on, embark upon, endeavor, engage in, enter,
   enter on, fall into, fall to, get busy, get cracking, get going,
   get under way, get with it, go about, go at, go in for, go into,
   go to it, go upon, have at, hop to it, jump to it, launch forth,
   launch into, lay about, light into, move into, pitch in,
   pitch into, plunge into, proceed to, sail into, set about, set at,
   set forward, set going, set to, set to work, start in, tackle,
   take on, take up, turn to, undertake, venture upon, wade into