PPP1R1B and Huntington disease: Moreover, the 6-week treatment regimen increased the immunodensity and protein levels of DARPP-32 (Fig. 2e and Supplementary Fig. 2d)—an MSN marker—and also reduced mtHtt aggregates (Fig. 2f and Supplementary Fig. 2b, c), a hallmark of HD pathology, in the striatum of HD R6/2 mice when compared with vehicle-treated HD mice.