TYRP1 and Alzheimer disease: While there is conflicting evidence regarding CatB in the development of AD, it should be pointed out that i) CatB was found to cleave Aβ42 into less amyloidogenic species [31], ii) the C-terminally truncated products Aβ38 and Aβ33 appear to be selectively cleaved from Aβ peptides by purified CatB [31, 34], and iii) production of the Aβ38 product corresponds with improved Aβ42 clearance in transgenic mice treated with the CatB-enhancing compound PADK [35].