adjoint equivalence

Hi, I have a question. If P and Q are objects in a 2-category C, and there is an equivalence between them, must there be an adjoint equivalence (an adjunction whose unit and counit are both isomorphisms) between them? Mac Lane answers this affirmatively in the case C = Cat, but, as far as I can tell, his proof doesn't generalize. Thanks for your help Paul -- Paul Blain Levy Université Paris 7 http://www.pps.jussieu.fr/~levy