tokens: BrdU = bromodeoxyuridine ; EGF = epidermal growth factor ; EGFR = epidermal growth factor receptor ; ERK = extracellular signal regulated kinase ; MAPK = mitogen activated protein kinase ; MEK = MAPK and ERK kinase ; MMP = matrix metalloproteinases ; MUC1 - CT = MUC1 cytoplasmic tail ; MUC1 - EX = MUC1 extracellular subunit ; PBS = phosphate - buffered saline ; PI = propidium iodide ; siRNA = small interfering RNA ; TIMP = tissue inhibitor of metalloproteinases ; TNF = tumor necrosis factor .