PTPRK and neoplasm: Beyond this, Storm et al.’s study in Nature focused on colorectal tumors lacking APC mutations but harboring PTPRK-RSPO3 fusion genes: RSPO3 fusions sustain high expression of intestinal stem cell marker genes (such as LGR5 and ASCL2) by continuously activating the Wnt signaling pathway, thereby driving tumor stem cell function and tumor growth.