  We study the existence of sign-changing solutions with multiple bubbles to
the slightly subcritical problem $$-\Delta u=|u|^{2^*-2-\e}u \hbox{in}\Omega,
\quad u=0 \hbox{on}\partial \Omega,$$ where $\Omega$ is a smooth bounded domain
in $\R^N$, $N\geq 3$, $2^*=\frac{2N}{N-2}$ and $\e>0$ is a small parameter. In
particular we prove that if $\Omega$ is convex and satisfies a certain
symmetry, then a nodal four-bubble solution exists with two positive and two
negative bubbles.
