FIGURE 4.

Functional consequences of PPM1A/B knockdown on huntingtin dephosphorylation downstream of D2R activation. A and B, HEK293T stable cell lines expressing an shRNA deprived of target in human cells (sh 936) or targeted against PPM1A (sh 494) (A) or expressing an shRNA against PPM1B (sh 1182) (B) were transiently transfected with 2 μg of HA-D2R and 2 μg of HTTN660-GFP. 48 h after transfection, cells were stimulated by 20 μm apomorphine (Apo) for 45 min. Then the cells were lysed, and the phospho-Ser-421 and HTT signals, as well as PPM1A/B knockdown relative to actin, were detected by Western blot. All data presented here are derived from 3–4 sets of independent experiments, and up to 6 sets in B.