  The Kalton-Peck $Z_2$ space is the derived space obtained from the scale of
$\ell_p$ spaces by complex interpolation at $1/2$. If we denote by by
$Z_2^{real}$ the derived space obtained from the scale of $\ell_p$ spaces by
real interpolation at $(1/2, 1/2)$, we show that $Z_2$ is the complexification
of $Z_2^{real}$. We also show that $Z_2^{real}$ shares the most important
properties of $Z_2$: it is isomorphic to its dual, it is singular and contains
no complemented copies of $\ell_2$.
