Cancer is an evolutionary disease. Disease-causing genetic or epigenetic changes often alter the functional characteristics of regulatory proteins leading to survival and proliferation of cancer cells at the expense of normal cells. The cancer-driving properties of cancer cells are selected for in specific cellular micro-environments by Darwinian natural selection. We study structural aspects of cancer proteins that make them targets for disease-causing mutations as well as their function in cancer cells. We also study how cellular interactions in micro-environments affect the function of cancer proteins. The work is relevant for understanding cancer development as well as development of resistance to chemotherapy. The work is focused on cancers involving blood cells.