A, HEK cells were transfected with tau and HDAC6-HA and treated with 1 μM MG132 for 0, 6, 16 or 24 h. Cell lysates were immunoprecipitated with HA antibody and immunoblotted as indicated. B, Quantification of the ratios of co-immunoprecipitated tau versus total input tau from three independent experiments described in panel A (mean ± SEM). Values were normalized to untreated group. Co-immunoprecipitated tau increased significantly after 16 h treatment compared with both untreated and 6 h treatment groups. *p<0.05. C, Perinuclear co-localization of HDAC6 and tau in MG132 treated cells. HEK cells were transfected with tau and HDAC6-HA and treated with 1 μM MG132 for 16 or 24 h followed by immunostaining with antibodies for tau (green) and HA (red). Nuclei were stained with DAPI (blue). Scale bar, 10 μm.