FIGURE 1.

TAZ is an unstable protein associated with β-TrCP. A, TAZ is an unstable protein. Both HeLa and MCF10A cells were treated CHX (20 μg/ml) for indicated times. Endogenous TAZ protein levels were determined. Relative TAZ levels were quantified by the ratio of TAZ to actin. B, MG132 increases TAZ protein levels in multiple cell lines. Cells were treated with either solvent DMSO or 10 μm MG132. Cell lysates were analyzed by Western blot (WB). Relative TAZ levels were normalized by actin and quantified by the ratio between with and without MG132 treatment. C and D, TAZ binds to β-TrCP. HA-β-TrCP was co-transfected with FLAG-TAZ into HEK293T cells as indicated. β-TrCP and TAZ associations were examined by reciprocal co-IP as indicated. E, Cullin-1 expression decreases TAZ protein levels. TAZ was co-transfected with different cullins as indicated. The steady state level of TAZ was determined by WB. F, β-TrCP knockdown increases TAZ protein levels. Three β-TrCP RNAi oligos were individually transfected into 293 cells as indicated. β-TrCP and TAZ levels were determined by WB. Relative TAZ level were quantified by the ratio of TAZ to actin.