  We present the main results of the first long-term spectrophotometric
monitoring of the ``Einstein cross'' Q2237+0305 and of the single-epoch spectra
of the lensed quasar J1131-1231.
  From October 2004 to December 2006, we find that two prominent microlensing
events affect images A & B in Q2237+0305 while images C & D remain grossly
unaffected by microlensing on a time scale of a few months. Microlensing in A &
B goes with chromatic variations of the quasar continuum. We observe stronger
micro-amplification in the blue than in the red part of the spectrum, as
expected for continuum emission arising from a standard accretion disk.
Microlensing induced variations of the CIII] emission are observed both in the
integrated line intensity and profile. Finally, we also find that images C & D
are about 0.1-0.3 mag redder than images A & B. The spectra of images A-B-C in
J1131-1231 reveal that, in April 2003, microlensing was at work in images A and
C. We find that microlensing de-amplifies the continuum emission and the Broad
Line Region (BLR) in these images. Contrary to the case of Q2237+0305, we do
not find evidence for chromatic microlensing of the continuum emission. On the
other hand, we observe that the Balmer and MgII broad line profiles are
deformed by microlensing. These deformations imply an anti-correlation between
the width of the emission line and the size of the corresponding emitting
region. Finally, the differential microlensing of the FeII emission suggests
that the bulk of FeII is emitted in the outer parts of the BLR while another
fraction of FeII is produced in a compact region.
