Bound vesicles subject to lateral farces such as arising from shear Row are
investigated theoretically by combining a lubrication analysis of the boun
d part with a scaling approach to the global motion. A minor inclination of
the bound part leads to significant lift due to the additive effects of la
teral and tank-treading motions. With increasing shear rate, the vesicle un
binds from the substrate at a critical value. Estimates are in agreement wi
th recent experimental data.