INPP1 and breast cancer: Inositol polyphosphate‐1‐phosphatase (INPP1) is an enzyme that dephosphorylates free polyphosphorylated inositols,6 key molecules involved in phosphatidylinositol signalling pathways.7 Presently, it has been reported that INPP1 is up‐regulated in human colorectal cancer.8 Daniel et al9 also found that INPP1 is highly expressed in aggressive melanoma, prostate, ovarian and breast cancer cells to promote migration and invasion; this finding suggests that INPP1 may function as an oncogene.