The modeling of protein expression and purification are core topics of the Fraunhofer Attract group "FAST-PEP". These topics are commonly divided into upstream production (USP) and downstream processing (DSP). Problems are frequently encountered at the interface of these areas, e.g. if highly effective product candidates cannot be purified economically. To avoid these issues, "FAST-PEP" also aims to link the data collected during expression and process development in order to take the requirements of DSP into account when optimizing USP and vice versa and also to continuously optimize the predictive models based on the increasing amount of information.