TI - Conclusion . AB - E2 -induced changes in breast cancer cell number [28] can be directly related to ERK1/2 activation/deactivation patterns and interacting signaling mechanisms . The differential behavior of cell lines expressing different levels of mER-alpha suggests a role for this receptor in the temporal coordination of phosphorylaTION/dePHOSphorylation events affecting the mitogen -activated kinases ERK1 and ERK2 .