(B) HeLa cells were depleted of UBQLN1 or UBQLN2 by siRNA transfection; depletion was verified by Western blot. Cells were starved for increasing periods of time, and their viability was analysed as in (A). The graph represents the mean of three experiments±s.e; *P0.05 between control and UBQLN2‐KD at 6 h (paired Student's t‐test). GAPDH, glyceraldehyde‐3‐phosphate dehydrogenase; GFP, green fluorescent protein; KD, knockdown; PI, propidium iodide; siRNA, short interfering RNA; UBQLN, ubiquilin. 