EGFR and cancer: To investigate EGFR-regulated miRNAs that are potentially involved in human cancer metastasis, we chose 4T1 mouse mammary cancer cell line, whose tumor growth and metastatic spread in BALB/c mice very closely mimic human breast cancer.18 This cell line spontaneously produces highly metastatic tumors that can metastasize to the lung, liver, lymph nodes and brain, preferentially the lung, while the primary tumor is growing in situ.