  High-energy hadronic reactions with proton-to-neutron transitions (and vice
versa) with small momentum transfer allow to study the properties of nearly
on-shell pions, which cannot be accessed otherwise. We overview the recent
results for such processes in deeply inelastic scattering, single and double
leading neutron production in pp collisions, including polarization effect. A
special attention is paid to the absorption effects, which are found to be much
stronger than what has been evaluated previously.
