Figure 2. Pentose phosphate pathway. The pentose phosphate pathway is the major source for the NADPH required for anabolic processes and is also responsible for the production of ribose-5-phosphate, which is an important part of nucleic acids. Finally the pathway can also be used to produce glyceraldehyde-3-phosphate, which can then be fed into the Krebs cycle and electron transport chain allowing for the harvest of energy. The effect of rapamycin exposure for 24 or 48 h is shown on isobar ribulose-5-phosphate, xylulose-5-phosphate (A), ribose-5-phosphate (B), ribose (C). See Figure 1 for color and legend code.