ELF3 and breast cancer: To elucidate whether ESE1 functions as a cytoplasmic regulator like previously reported in breast cancer or as a nuclear transcriptional factor like most other ETS proteins, we examined the expression of endogenous ESE1 localization by IF and immunoblot analysis of the nuclear and cytoplasmic extracts in L3.6, PANC‐1, and CFPAC‐1.