PTK6 and breast lobular carcinoma: A significant proportion of ductal and lobular carcinoma samples that stained positive for Brk also co-stained with phospho-p38 MAPK; Brk-positive tumors are 2.87 times more likely to be phospho-p38-positive than Brk-null tumors are likely to be phospho-p38-positive (P = .03).