  We studied the crystallization of a globular protein, lysozyme, in the cubic
phase of the lipid monoolein. The solubility of lysozyme in salt solution
decreased by a factor of $\sim 4$ when confined in cubic phase. Calculations
and Monte Carlo simulations show that this can be explained by the {\it
confinement} of lysozyme molecules to the narrow water cells in the cubic
phase.
