MAPT and red-green color blindness: Of note, P-S262 alone (without Ub-K267) was elevated in CBD and FTLD; but in AD, P-S262 was systematically associated to Ub-K267 in soluble tau, making the combination of Ub-K267 and P-S262 a PTM event specific for AD (Fig. 6a and Fig. 4).