We have determined elasticity data of various ovalbumin gels as a function of concentration of ovalbumin and analyzed these data in terms of a percolation model. In addition, we have analyzed elasticity data of a multitude of other protein gels. We find that all data can be described by one percolation model. The critical exponent is 1.79 +/- 0.25, in accordance with isotropic percolation. The value of the critical percolation threshold varies by an order of magnitude. The findings suggest that the effects of external fields on gelation can be captured by the effects of these external fields on the critical percolation threshold.