CLN5 and central nervous system cancer: It has been reported that: (1) BMP ligands are differentially expressed in tumor versus healthy tissue with a neat clinical relevance [18, 19]; (2) activation of the BMP pathway reduces glioma cell proliferation in vitro and in vivo and induces differentiation of the GBM-TICs [4, 7, 20–22] and (3) BMPs render GBM-TICs more susceptible to conventional therapy [23, 24] (for a review see [25]).