Figure 3. Gln deprivation promotes the serine pathway.

(A) Representative gel resulting from a 2D-DIGE experiment comparing the proteome of HL-60 cultured in the absence of Gln or Glc; proteins overexpressed in the absence of Gln indicated by an arrow (left) are listed (right) with indication of the fold-change (P < 0.05). (B) Scheme of the serine pathway from 3-phosphoglycerate (3PG). Representative immunoblots for (C) PHGDH and (D) PSAT in HL-60 leukemia cells incubated for 48 hours in medium containing the indicated decreasing concentrations of Gln. (E) Representative immunoblots for PHGDH in HL-60 leukemia cells exposed for 48 hours (in medium containing Glc and/or Gln) to the indicated increasing concentrations of L-asparaginase. Representative immunoblots for (F) ATF4 and (G) phospho-eIF2 after 6 hours Gln withdrawal in HL-60 leukemia cells. The immunoblot experiments were repeated 2–3 times with similar results.