RYK and glioma: RYK controls fundamental biological processes, including neuronal differentiation and axon outgrowth [13, 14], and its deregulation has been proven to be associated with cancer: indeed, RYK is overexpressed in ovarian cancer tissues [15], is essential for WNT-5a-dependent invasiveness in glioma, and its expression correlates with the WHO's histological grading system for glioma tissues [16].