With no explanation, label each line with "O", "other-biologything", "other-medical", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart" or "building-airport" preceded by ":".
This
block
of
nucleotide
biosynthesis
is
more
toxic
to
rapidly
growing
cells
than
non-dividing
cells
,
since
a
rapidly
growing
cell
has
to
carry
out
DNA
replication
,
therefore
methotrexate
is
often
used
in
cancer
chemotherapy
.
This:O
block:O
of:O
nucleotide:other-biologything
biosynthesis:O
is:O
more:O
toxic:O
to:O
rapidly:O
growing:O
cells:O
than:O
non-dividing:O
cells:O
,:O
since:O
a:O
rapidly:O
growing:O
cell:O
has:O
to:O
carry:O
out:O
DNA:other-biologything
replication:O
,:O
therefore:O
methotrexate:other-biologything
is:O
often:O
used:O
in:O
cancer:other-medical
chemotherapy:other-medical
.:O