Fig. 2
From: Bortezomib resistance in multiple myeloma is associated with increased serine synthesis
Bortezomib-resistant cells have an enhanced activity of the pentose phosphate pathway. Intra- and extracellular metabolite analysis of RPMI-8226 wild type (WT) and bortezomib resistant (BTZ/100) cells. Cells were suspended in DMEM containing 8 mM [U-13C] D-glucose. a, b Media samples were collected after 8 h, followed by LC-MS analysis of extracellular glucose (a) and lactate (b). Results represent % peak area ± SD compared to cell-free media (n = 3). Unpaired t-tests were performed (* = p < 0.05, ** = p < 0.01,). c Intracellular metabolites were extracted after 4 and 8 h and analyzed by LC-MS. Data are means ± SD (n = 3) of unlabeled (white) and 13C- labeled metabolites (gray). AMP = adenosine monophosphate, GMP = guanosine monophosphate, PPP = pentose phosphate pathway, TCA = tricarboxylic acid