ELF5 and breast carcinoma: We have recently described a pro-metastasis pathology we called involution mimicry [39] that occurs in response to forced expression of the ETS transcription factor ELF5, the master regulator of lobuloalveolar development during pregnancy, which causes a limited lactation and ongoing involution response in an ELF5 mouse model [23], but is also seen in breast cancer patients.