MAPT and neuroblastoma: To assess potential effects of CatD proteolytic activity on human tau (hTau) catabolism in living cells, we studied the M1C cell model, a human neuroblastoma (BE(2)-M17D) cell line that expresses the human 4R0N tau isoform in a tetracycline (Tet)-dependent (Tet-Off) manner [36].