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Study Information
Study Attribute Value
CEBS Accession Number: 002-01553-0001-0000-7
Chemical Name: 6-Mercaptopurine
CASRN: 50-44-2
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 310403_SCE
Study Result: Positive

Study Result: Positive
Activation Trial Trial Call
No Activation  1  Negative 
No Activation  2  Positive 
No Activation  3  Positive 
Induced Rat Liver S9  1_S9  Negative 

Trial #: 1    Activation: No Activation    Date: 05/20/1986    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1046 448 0.428 8.96 26.5 0.000
Test Chemical 6-Mercaptopurine 
 0.16      
 50 1048 425 0.406 8.50 26.5 -5.315 
 0.5       
 50 1051 493 0.469 9.86 26.5 9.521 
1.6       
 0 0 0 0.000 0.00 26.5 N/A
Positive Control Mitomycin-C 
 0.0E-4    
 50 1050 632 0.602 12.64 26.5 40.534
Mitomycin-C 
 0.005     
 10 210 327 1.557 32.70 26.5 263.565
Trend: 1.414        
Probability: 0.079        

Trial #: 2    Activation: No Activation    Date: 07/02/1986    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1049 469 0.447 9.38 26.0 0.000
Test Chemical 6-Mercaptopurine 
 0.16      
 50 1049 489 0.466 9.78 26.0 4.264 
 0.5       
 50 1048 727 0.694 14.54 31.0 55.159 
1         
 50 1049 807 0.769 16.14 31.0 72.068 
1.6       
 17 356 290 0.815 17.06 31.0 82.201
Positive Control Mitomycin-C 
 0.0E-4    
 50 1050 596 0.568 11.92 26.0 26.958
Mitomycin-C 
 0.005     
 10 207 344 1.662 34.40 26.0 271.698
Trend: 12.392        
Probability: 0.000        

Trial #: 3    Activation: No Activation    Date: 10/19/1988    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1015 429 0.423 8.58 26.0 0.000
Test Chemical 6-Mercaptopurine 
 0.15      
 50 1029 710 0.690 14.20 31.0 63.249 
 0.5       
 29 605 500 0.826 17.24 31.0 95.534 
1         
 0 0 0 0.000 0.00 31.0 N/A 
1.6       
 0 0 0 0.000 0.00 31.0 N/A
Positive Control Mitomycin-C 
 0.0E-4    
 50 1037 635 0.612 12.70 26.0 44.878
Mitomycin-C 
 0.005     
 10 210 278 1.324 27.80 26.0 213.209
Trend: 10.097        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 05/06/1986    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Dimethyl Sulfoxide 
0         
 50 1042 505 0.485 10.10 26.0 0.000
Test Chemical 6-Mercaptopurine 
16         
 50 1049 488 0.465 9.76 26.0 -4.011 
50         
 50 1049 482 0.459 9.64 26.0 -5.191 
160         
 50 1049 530 0.505 10.60 26.0 4.250 
500         
 50 1050 515 0.490 10.30 26.0 1.203
Positive Control Cyclophosphamide 
 0.1       
 50 1037 611 0.589 12.22 26.0 21.573
Cyclophosphamide 
 0.6       
 10 212 269 1.269 26.90 26.0 161.814
Trend: 0.769        
Probability: 0.221