PTK2B and breast cancer: EGF activates Pyk2, regulates functions of downstream Twist‐1,2, CD44, Snail‐1,2, matrix metalloproteinase‐10 (MMP‐10), β‐catenin, fibronectin, vimentin, E‐cadherin, ZO‐1, and Zeb‐1,2, promotes EMT, migration, invasion, and metastasis of breast cancer cells.