In order to investigate whether the expression levels of HAS2, USP17 and USP4 are correlated, we investigated their expressions in normal human lung fibroblasts and breast epithelial cells (MCF10A), as well as in breast cancer (MCF7, HS578T, MDA-MB-231-BM) and lung cancer (H1299 and A549) cells by immunoblotting. Here, USP4 is linked to lung cancer.