George Rathmann, is the scientist at Amgen who pushed for development of EPO, a hormone which stimulates red blood cell production, when the bio-tech venture company was struggling in the mid-1980's. After approval by the EPA in 1989, Epogen became Amgen's main product with sales of $2 billion in 2011. Rathmann graduated from Northwestern University, and received his PhD. from Princeton University in physical chemistry. He helped develop Scotchguard at 3M, and later headed the R&D department at the diagnostics division of Abbott Laboratories. He built Amgen from a staff of four in the early days in 1980, and it was his intuitive sense that Amgen should focus its entire effort on EPO development in the mid-1980's that led to its success.