  Both the pairing and the pair-breaking modes lead to similar kinks of the
electron dispersion curves in superconductors, and therefore the photoemission
spectroscopy can not be straightforwardly applied in search for their pairing
glue. If the momentum-dependence of the normal and anomalous self-energy can be
neglected, manipulation with the data does allow us to extract the gap function
$\Delta(\omega)$ and therefore also the pairing glue. However, in the
superconducting cuprates such procedure may not be justified. In this paper we
point out that the pairing glue is more directly visible in the spectral
function of the Nambu-Gor'kov anomalous propagator and we demonstrate that this
function is in principle experimentally observable.
