The study by
Colombo and colleagues shows that
PFKFB3 levels and, consequently, glycolysis,
are elevated in mid- to late G1
and decrease during S phase. One
possible explanation for this behavior
is that, by switching off the glycolysis
pathway, glucose is diverted into the
pentose phosphate pathway and
PFKFB3 levels and,
consequently, glycolysis,
are elevated in mid- to
late G1 and decrease
during S phase.
converted to ribose-5-phosphate for nucleotide
synthesis. Alternatively, it may be
used to provide carbons for fatty acid
synthesis. Unlike glucose, glutamine is
required for the G1/S transition and
throughout S phase (5). These observations
suggest different roles for the metabolic
pathways at distinct phases of the
cell cycle. It will be interesting to determine
whether nonmalignant cells also
use these mechanisms to regulate energy production and macromolecular precursor
biosynthesis.