Many cancer patients lose a lot of weight while sick. They lose not only body fat but also muscle mass, and when this happens, they do not heal as well and cancer treatments are less effective. It is therefore of great importance to identify cancer patients that will suffer from muscle wasting early and to develop treatments that will help preserve body weight and muscle mass. To do this, scientists must first understand what causes some cancer patients to develop muscle wasting. Our research focuses on understanding how a tumour damages the muscle. We have found that some tumours release products which stimulate the immune system and in muscle cause a protein called C/EBPbeta to persist in muscle stem cells. This expression prevents these satellite cells from acting to repair muscle and so muscle damage is not repaired. Over time, the muscle becomes weaker and smaller. The objectives of this proposal are to explore the mechanisms by which C/EBPbeta regulates muscle stem cell function in healthy muscle and to understand how tumours prevent normal stem cell function.