MMP9 and breast cancer: The role of USP4 in many pathological and physiological processes has been reported; USP4 promotes breast cancer invasive migration through the relaxin2-mediated TGF-β1/Smad2/MMP-9 pathway [31]; USP4 inhibits myogenic cell differentiation by catalyzing MyoD activity [32]; The H19/miR-148a/USP4 axis promotes hepatic stellate cells by enhancing and TGF-β signaling in hepatocytes to promote liver fibrosis [33].