Figure 5. HDAC4 decreases the stability of MAP1S protein. (A, B) MAP1S depletion has no effect on HDAC4 levels in HeLa cells treated with MAP1S-specific siRNA (A) or MEF cells derived from wild-type or MAP1S−/− mice (B). (C) Overexpression of MAP1S isoforms has no impact on levels of HDAC4 in HeLa cells. (D, E) Increasing expression of HDAC4 causes dose-dependent reduction in levels of MAP1S in 293T cells. Representative immunoblots (D) and quantification (E) are shown. (F) HDAC4 depletion with siRNA increases levels of MAP1S in HeLa or COS7 cells. (G) HDAC4 suppression or overexpression does not alter levels of MAP1S mRNA. The relative levels of MAP1S mRNA in HeLa cells transfected with siRNA to suppress the expression of HDAC4 or with plasmid for HDAC4 overexpression. (H, I) HDAC4 depletion increases the stability of MAP1S proteins. HeLa cells were treated with random (Mock) or HDAC4-specific siRNA (HDAC4), and cellular protein translation was then terminated with cycloheximide (CHX). Samples were collected at different times after cycloheximide treatment. Representative immunoblots (H) and quantification (I) are shown.