Our latest work on drug release testing of microparticles was just accepted by the International Journal of Pharmaceutics. A great work by the young first author Ge Fiona Gao. One year ago she won a Best Abstract Award of the AAPS Annual Meeting, now she has finalized her work. The release assay elucidated the influence of proteins on microparticle release and how they affect discrimination between different batches of drug products. Even without affecting solubility, proteins stabilize particles and may affect the performance in the subcutaneous tissue. A mechanistic model helped us to understand the influences of such parameters and formulation characteristics on pharmacokinetics.