Proteins as biotherapeutics Proteins are promising biotherapeutics offering advantages such as selectivity, specificity and potency. A number of protein therapeutics are currently marketed and projected to acquire a major share of the pharmaceutical market in the future. Design, development and production of protein biologics has reached advanced stages due to advances in protein characterization [1,2], process control [3] and manufacturing technology [4]. The pharmaceutical/biotechnology industry invested nearly US$150 billion in the past 3 years for R&D of new therapeutic molecules including biopharmaceutical R&D. As a result, more than 907 biotherapeutics are currently in the various phases of clinical trials. Despite excellent therapeutic characteristics such as selectivity, specificity and potency,and fast-paced development and production, success with protein biotherapeutics in treating diseases is limited.