  The well-known theorem of Johnson, Palmer and Sell asserts that the endpoints
of the Sacker--Sell spectrum of a given cocycle of invertible matrices over a
topological dynamical system $(M, f)$ are realized as Lyapunov exponents with
respect to some ergodic invariant probability measure for $f$. In this note we
establish the version of this result for quasicompact cocycles of operators
acting on an arbitrary Banach space.
