  We propose a novel electron-phonon interaction arising from the modulation of
the superexchange interaction by phonons. It is enhanced by spin and
superconducting fluctuations, which are developed mainly because of the
superexchange interaction. It must be responsible for the softening of phonons
and kinks in the dispersion relation of quasi-particles. However, the
superexchange interaction must be mainly responsible for the formation of
Cooper pairs.
