Systems Biology is an interdisciplinary approach to understand biological processes that act on different scales. For example biochemical pathways steer internal cell dynamics, which can lead to cell movement. Cell movement can lead to cancer invasion and cancer invasion can lead to a disease that affects the whole body. To understand such a process, a multiscale approach is needed which can bridge the scales while retaining the complexity of the biological system. This approach is available in applied mathematics where multiscale methods have a long history. The language of Systems Biology is mathematics and it is on us to make use of these exciting mathematical methods to help to understand biological systems.