  A ToO observation of the TeV-emitting blazar Mrk 421 with INTEGRAL was
triggered in June 2006 by an increase of the RXTE count rate to more than 30
mCrab. The source was then observed with all INTEGRAL instruments with the
exception of the spectrometer SPI for a total exposure of 829 ks. During this
time several outbursts were observed by IBIS and JEM-X. Multiwavelength
observations were immediately triggered and the source was observed at radio,
optical and X-ray wavelengths up to TeV energies. The data obtained during
these observations are analysed with respect to spectral evolution and
correlated variability. Preliminary results of the analysis are presented in
this poster.
