The book "Recombinant Protein Solubility and Conformational Quality" by Elena Garcia Fruitos offers a comprehensive analysis of the challenges and opportunities in the production of recombinant proteins in transgenic cells. It examines how these cells can serve as a cost-effective and unlimited source of valuable proteins. A central theme of the book is the formation of insoluble aggregates, known as inclusion bodies (IBs), which often occur during production in bacteria. The author highlights the biological activities of these aggregates and their relationship to soluble proteins in Escherichia coli. Through a detailed analysis of protein aggregation and the role of DnaK in proteolysis, a new understanding of the concepts of solubility, aggregation, and conformational quality is developed. The book also proposes utilizing inclusion bodies as potential biocatalysts, opening new perspectives for biotechnological applications.