Rogers was exposed to a controlled burst of "Vita-Rays" that activated and stabilized the chemicals in his system. The process successfully altered his physiology from its frail state to the maximum of human efficiency, including greatly enhanced musculature and reflexes. Soon after, Professor Erskine was assassinated by a Nazi operative, leaving Steve the sole beneficiary of Erskine’s genius. Renamed “Project: Rebirth,” variations of the Super-Soldier serum were subsequently tested, under inhuman conditions, on African-American soldiers. The most successful of these was Isaiah Bradley, and Project: Rebirth’s resources were eventually absorbed into a multinational superhuman research project dubbed Weapon Plus.
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