Description
Cancer cell motility and invasiveness are fundamental characteristics of the malignant phenotype and are regulated through diverse signaling networks involving kinases and transcription factors. In this study, we identify a nuclear hormone receptor (ER)-protein kinase (ERK5)-cofilin (CFL1) network that specifies the degree of breast cancer cell aggressiveness through coupling of actin reorganization and hormone receptor-mediated transcription. Using dominant negative and constitutively active forms, as well as small molecule inhibitors of ERK5 and MEK5, we show that hormone activation of estrogen receptor- determines the nuclear versus cytoplasmic localization of the MAPK family member ERK5, which functions as a coregulator of ER-gene transcription.