With no explanation, label each line with "O", "other-biologything", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
It
is
caused
by
mutations
in
the
CFTR
protein
,
a
chloride
channel
expressed
in
epithelial
cells
.
It:O
is:O
caused:O
by:O
mutations:O
in:O
the:O
CFTR:other-biologything
protein:other-biologything
,:O
a:O
chloride:O
channel:O
expressed:O
in:O
epithelial:O
cells:O
.:O