A protein called the type I insulin-like growth factor receptor (IGF-IR) is frequently found at high levels in human breast cancer. To study how IGF-IR influences breast cancer development and progression we have created mice that express higher than normal levels of this protein in their mammary glands. High levels of the IGF-IR induce tumour development in the mammary glands of mice and metastatic spread to the lungs. What remains unclear is how IGF-IR causes mammary tumours to develop and spread to the lungs. One protein that is activated by IGF-IR is Akt. There are 3 different forms of Akt which may mediate different properties in tumour cells such as growth and invasion. This project will examine whether tumour growth and metastasis is regulated by specific forms of Akt. By understanding the signals that stimulate tumour growth and/or metastasis, better screening and therapeutic strategies can be developed.