Figure 8.

Ca²⁺/calpain functions in pVHL-containing HEK293 and RCC4/VHL cells. HEK293 cells were pretreated with 1 mM PHD hydroxylase inhibitor DMOG for 1 h or remained as a control. Afterward, incubations continued for 1 h in the presence of DMOG alone or in the presence of DMOG with the addition of (A–C) 10 nM or 30 nM thapsigargin, (B) 100 nM calpain inhibitor ALLM, (C) 10 μM of the 26S proteasome inhibitor lactacystin, or 2 μM calpain inhibitor calpastatin peptide. Western analysis was used to follow the expression of HIF-1α and IκBα. (D) RCC4/VHL cells were pretreated for 1 h with 1 mM DMOG or 30 nM thapsigargin, or remained as a control. Pretreated cells were further exposed to DMOG alone, to DMOG with the addition of 30 nM thapsigargin, to DMOG with the addition of 30 nM thapsigargin and 10 μM lactacystin or 2 μM calpastatin peptide. Western analysis was used to follow the expression of HIF-1α and IκBα. Results are representative for three individual experiments.