Early, it has been suggested that Keplerian flows should be
unstable regarding shear instabilities. This hypothesis, not seriously
considered nowadays, is strongly sustained by a recent re-analysis of
experimental data on shear flows and new laboratory experiments. We
review some consequences on steady state accretion dises of a viscosity
law derived from shear experiments. In particular, we show that
it wholly suppresses the thermal and viscous instabilities within the
radiation pressure dominated region, unlike the standard theory.