The present invention provides the use of RNA removal to initiate protein aggregation of a plurality of proteins in a cell or cell lysate. This may be used to create an in vitro model of a disease, such as a neurodegenerative disease. The present invention also provides a method for determining the efficacy of a potential anti-protein aggregation agent comprising the following steps: i) using RNA removal to initiate the aggregation of a protein in a cell or cell lysate, ii) treating the cell or cell lysate with the potential anti-protein aggregation agent before, after or during RNA removal; and iii) comparing protein aggregation in equivalent samples with and without step ii) treatment in which a decrease in protein aggregation associated with step ii) treatment indicates that the potential anti-protein aggregation agent is effective in preventing and/or reversing protein aggregation.