Have you ever wondered how you became a complex human being from a tiny fertilized egg? Well, the fertilized egg divides and grows making more and more cells. Some of these cells further specialize into the heart, for example, while other cells give rise to the spinal cord. But we don’t know exactly how these cells are able to do this. And this knowledge is important to learn more about organ development, embryo development and birth defects. Studying this in real embryo’s is restricted for ethical and legal reasons. Therefore, I use human stem cells, which are able to form any cell type in the human body. Under specific conditions, these stem cells can form embryo-like structures. And although these embryo-like structures are simplified representations of an actual embryo, we can now study the early stages of human embryonic development. I focus on studying proteins. Think of proteins as the architects and builders that shape the foundation of our bodies. By studying how these proteins function and their interaction, we can learn more about what causes birth defects and diseases.