The 243 words that appeared in at least one million PubMed records as of July 28, 2018. The words are ranked by number of appearances (second column).

the	139211417
of	112854806
and	84215510
in	70197546
to	47013634
a	41370842
with	30246472
was	24206336
for	22600525
were	21471088
that	18280936
is	18227406
by	17271385
as	12016804
on	12011786
patients	11772152
from	11384398
this	11080346
or	10218358
are	9712259
at	9561066
be	9237307
an	9120830
we	7971299
these	7021680
not	6852516
cells	6522511
study	5647890
which	5448562
have	5437508
after	5374766
than	5300838
between	5091970
but	4331569
been	4260206
treatment	4198501
results	4185004
has	4101120
both	4062938
it	4010595
cell	3973786
may	3967672
two	3936405
using	3926556
group	3886116
also	3768744
had	3746995
during	3673771
p	3642899
all	3630831
no	3610491
their	3529102
more	3502410
used	3370307
activity	3290340
can	3259258
increased	3077182
protein	3024529
data	2976588
levels	2963447
other	2959613
found	2935639
significantly	2924095
one	2922048
disease	2865062
compared	2830223
significant	2827122
expression	2800756
clinical	2766556
analysis	2749713
effect	2630638
associated	2596587
effects	2574152
showed	2569343
there	2567762
different	2533871
when	2520858
studies	2517174
only	2503235
its	2465530
high	2449757
however	2415170
control	2409254
into	2333829
human	2330337
most	2320956
years	2317051
observed	2262764
time	2251421
cases	2223890
use	2139026
our	2130563
higher	2111852
blood	2097518
three	2095536
gene	2086885
groups	2070575
rate	2058700
such	2057454
age	2056815
risk	2027796
response	2015487
present	2015185
cancer	1988391
those	1986315
who	1900390
increase	1897366
well	1895506
system	1885422
changes	1838271
normal	1805545
respectively	1797362
patient	1793817
first	1784158
model	1773740
mean	1760305
role	1756578
acid	1722207
factors	1695355
total	1693498
lt	1672831
function	1668194
method	1663526
among	1631804
less	1620337
new	1620330
health	1618167
within	1617889
could	1612097
number	1601898
each	1596390
level	1595269
did	1582759
therapy	1581414
development	1570824
performed	1570596
low	1561433
growth	1556000
suggest	1538257
important	1520166
mice	1502261
type	1499730
days	1494287
dna	1492973
c	1487168
rats	1481174
similar	1459274
lower	1444203
while	1442701
they	1442228
some	1434626
without	1432893
presence	1431229
children	1424913
months	1418450
women	1408717
specific	1384677
proteins	1377592
potential	1364948
through	1362519
obtained	1360884
studied	1359836
tumor	1358059
serum	1355450
tissue	1353872
reported	1352687
over	1347688
binding	1329663
including	1328077
subjects	1327074
reduced	1326587
n	1314948
factor	1314489
concentrations	1313250
based	1310910
plasma	1309973
findings	1308349
identified	1293750
receptor	1292837
differences	1285132
care	1282476
although	1281871
treated	1281029
decreased	1275425
test	1271496
measured	1266414
about	1243132
addition	1223951
under	1216766
further	1215473
primary	1212694
early	1209869
concentration	1209194
due	1203742
case	1188526
h	1185805
diagnosis	1182783
following	1182221
genes	1181656
infection	1173398
conditions	1170146
b	1169537
show	1168019
period	1151375
should	1149338
related	1147987
either	1145130
induced	1140860
examined	1136616
four	1135782
evidence	1132120
investigated	1126739
positive	1126392
developed	1125151
range	1118986
demonstrated	1115545
determined	1113135
revealed	1112304
several	1110977
activation	1098957
samples	1078910
liver	1071566
surgery	1069711
same	1065857
major	1065607
before	1056801
values	1052409
greater	1043618
survival	1037913
species	1037851
shown	1034245
acute	1032722
per	1031331
determine	1030907
brain	1030730
population	1025505
t	1024468
complex	1021814
pressure	1021473
bone	1016619
whereas	1010808
vitro	1006285
drug	1005902