  We investigate an electrostatically defined quantum point contact in a
high-mobility InSb two-dimensional electron gas. Well-defined conductance
plateaus are observed, and the subband structure of the quantum point contact
is extracted from finite-bias measurements. The Zeeman splitting is measured in
both in-plane and out-of-plane magnetic fields. We find an in-plane g factor
$|g_{\parallel}^* | \approx$ 40. The out-of-plane g factor is measured to be
$|g_{\perp}^* | \approx$ 50, which is close to the g factor in the bulk.
