The red area is a milk duct surrounded by connective tissue in a biopsy from a patient with breast cancer. Connective tissue cells are green and collagen fibres, turquoise. When a cancer starts in duct tissue some cells move away from the main mass of the tumour and can push out through the connective tissue and head off around the body. This is called metastatis and is a very dangerous phase of cancer as the migrating cells can start tumours in other parts of the body. Dr Lilian Soon and her team are investigating how this happens.