“…Before EPO received market approval in the 1990s, several studies had already been done to develop animal-free methods to assess EPO potency (entrepreneurial activity). It had taken decades of research to correlate the potency of protein medicines in animals with the results of animal-free methods (knowledge development), and the development of animal-free methods for EPO potency testing showed additional difficulties (Barth et al, 2007). The potency of most protein medicines depends only on binding affinity and signal transduction, whereas for EPO potency there is also a strong, but not fully understood, correlation between glycosylation and potency (Imai et al, 1990;Watson and Yao, 1993;Barth et al, 2007;Ferretto et al, 2009, Industry1, 2011.…”