Figure 1.

Possible mechanisms of transformation mediated by the JSRV Env protein. (a) HYAL2 normally functions to suppress cell growth. The mechanism by which suppression is mediated is not known, but one possibility is that Env-HYAL2 binding and virus entry blocks interaction with a ligand that could be soluble (as illustrated by the purple diamond) or cell-associated. (b) Env-HYAL2 interaction stimulates cell growth and mediates virus entry. (c) Env-HYAL2 interaction mediates virus entry, and Env interaction with another cellular protein stimulates cell growth. Although interaction with a cell surface molecule is illustrated, this interaction need not occur at the cell surface.