For any semisimple Lie algebra, there is a family of maximal commutative subalgebras of its universal envelopping algebras. These can be used to construct special bases of representations, generalizing the Gelfand-Zetlin basis for gl_n. By varying in this family, we obtain an action of the cactus group on these bases. This action of the cactus group matches an action defined combinatorially using crystals.