SEZ6 and nasopharyngeal carcinoma: Although, in our study, we did not detect an increase in BACE1 protein levels in NPC1 vs. wt mice, our results demonstrate significantly increased processing of the exclusive BACE1 substrates Sez6 and Sez6L, as well as APP, in NPC1 mice, suggesting that BACE1-dependent cleavage in this mouse model of NPC disease is enhanced.