  We have combined multi-wavelength observations of a selected sample of
starforming galaxies with galaxy evolution models in order to compare the
results obtained for different SFR tracers and to study the effect that the
evolution of the starforming regions has on them. We also aimed at obtaining a
better understanding of the corrections due to extinction and nuclear activity
on the derivation of the SFR. We selected the sample from Chandra data for the
well studied region Chandra Deep Field South (CDFS) and chose the objects that
also have UV and IR data from GALEX and GOODS-Spitzer respectively.
  Our main finding is that there is good agreement between the extinction
corrected SFR(UV) and the SFR(X), and we confirm the use of X-ray luminosities
as a trustful tracer of recent star formation activity. Nevertheless, at
SFR(UV) larger than about 5Msol/year there are several galaxies with an excess
of SFR(X) suggesting the presence of an obscured AGN not detected in the
optical spectra. We conclude that the IR luminosity is driven by recent star
formation even in those galaxies where the SFR(X) is an order of magnitude
higher than the SFR(UV) and therefore may harbour an AGN. One object shows
SFR(X) much lower than expected based on the SFR(UV); this SFR(X) `deficit' may
be due to an early transient phase before most of the massive X-ray binaries
were formed. An X-ray deficit could be used to select extremely young bursts in
an early phase just after the explosion of the first supernovae associated with
massive stars and before the onset of massive X-ray binaries.
