  We present recent results from spectroscopic data and modeling of the
biconical ionized gas in the Seyfert-2 galaxy NGC 4388. A field of ~2.6 x 2.4
kpc centered on the nucleus has been observed by means of the modern technique
of integral field spectroscopy. The analysis of more than two hundred spectra
allowed to study the physical characteristics of the gas in the surroundings of
the active nucleus. The South-West ionization cone, revealed by the [O
III]5007/H-beta excitation map, shows high emission line ratios not completely
supported by simple photoionization. Composite models which account for the
combined effects of photoionization and shock show that such high [O
III]/H-beta line ratios are emitted by low density (n_0=30 cm^-3) gas inside
large (D > 1 pc) shocked clouds (V_s=100 km/s) reached by a relatively low flux
from the active nucleus. The data of the VEELR in the North-East cone by
Yoshida et al. (2002) have been modeled. The results confirm that
photoionization is the prevailing mechanism, but nontheless weak shocks are
under way between colliding clouds with small (< 1 pc) sizes and low densities
n_0 <= 100 cm^-3, moving outward at relatively low velocities (V_s=100 km/s).
