  The detection of gamma-ray emission from narrow-line Seyfert 1 galaxies
(NLSy1) has challenged the idea that large black hole (BH) masses ($\ge$10$^8$
M$_{\odot}$) are needed to launch relativistic jets. We present near-infrared
imaging data of the gamma-ray-emitting NLSy1 PKS 1502+036 obtained with the
Very Large Telescope. Its surface brightness profile, extending to $\sim$ 20
kpc, is well described by the combination of a nuclear component and a bulge
with a Sersic index $n$ = 3.5, which is indicative of an elliptical galaxy. A
circumnuclear structure observed near PKS 1502+036 may be the result of galaxy
interactions. A BH mass of about $\sim 7 \times 10^{8}$ M$_{\odot}$ has been
estimated by the bulge luminosity. The presence of an additional faint disc
component cannot be ruled out with the present data, but this would reduce the
BH mass estimate by only $\sim$ 30%. These results, together with analogous
findings obtained for FBQS J1644+2619, indicate that the relativistic jets in
gamma-ray-emitting NLSy1 are likely produced by massive black holes at the
center of elliptical galaxies.
