In various cancers, similar to the other ErbB’s, HER4’s activation can stimulate tumor growth and aggressiveness (osteosarcoma, melanoma, and tumors of the stomach, ovary, colon, thyroid, and CNS [medulloblastomas, ependymoma, and gliomas]) [4,6,11,12,13,14,15,16]. Here, EGFR is linked to cancer.