Nuclear localization of KLF4 is associated with an aggressive phenotype in early-stage breast cancer.

Purpose: The Krüppel-like transcription factor KLF4/GKLF induces both malignant transformation and a slow-growth phenotype in vitro. Although KLF4 expression is increased in most cases of breast cancer, it was unknown whether these cases represent a distinct subtype with a different clinical outcome.

Experimental Design: We examined expression of KLF4 by immunostaining 146 cases of human primary infiltrating ductal carcinoma of the breast.