We present recent results from spectroscopic data and modeling of the biconical ionized gas in the Seyfert-2 galaxy NGC 4388 .
A field of \sim 2.6 \times 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 ] \lambda 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 ( \mathrm { n _ { 0 } } =30 \mathrm { cm ^ { -3 } } ) gas inside large ( D > 1 pc ) shocked clouds ( \mathrm { V _ { s } } =100 \mathrm { km s ^ { -1 } } ) 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 \mathrm { n _ { 0 } } \leq 100 \mathrm { cm ^ { -3 } } , moving outward at relatively low velocities ( \mathrm { V _ { s } } =100 \mathrm { km s ^ { -1 } } ) .