  The pion cloud is important in nuclear physics and in a variety of low-energy
hadronic phenomena. We argue that it is natural to expect it to also be
important in lepton-proton deep inelastic scattering and Drell-Yan studies of
proton structure. We compute the necessary consequences of the pion cloud in
connection with the recent SeaQuest data. The effects are detailed by using the
exact kinematics of the experiment. Good agreement with the measurements is
obtained. Thus the universality of pionic effects is understood.
