(A) HeLa cells expressing GFP‐tagged UBQLN1 or UBQLN2 (or GFP for controls) were transferred to starvation medium (PBS) for the indicated time. Where specified, only serum was removed from the culture medium. Viability of transfected cells was assessed by PI staining and analysed by flow cytometry. The graph represents the mean of three experiments±s.e. 