As seen in X-Factor (Vol 1) #86.
*X-Cutioner's Song
It began when the X-Men's founder, Charles Xavier, was shot by Cable, the warrior from the future - or so it seemed. But the assassin was really Cable's clone, the terrorist Stryfe, who next captured their parents, Cyclops and Jean Grey. Yet Xavier survived, and the X-Men, X-factor and X-Force tracked Stryfe to his lunar base, where Cable nearly perished while trying to destroy him. *Source: Back of Card