TM9SF4 and cancer: The paradox is that previous research has reported that TM9SF4, a key gene involved in cancer cell cannibalism, is a novel V-ATPase-interacting protein that regulates tumor pH alterations associated with drug resistance and invasiveness of colon cancer cells [16], and PALGL2, a prognostic factor, can serve as a tumor oncoprotein in the development and progression of colorectal cancer [17].