CYP2A6 and lung cancer: Similarly, urinary total NNAL decreased with CYP2A6 activity for both African Americans (P = 0.0008) and Japanese Americans (P = 0.0158, Fig. 4d).7 Interestingly, TNE values for the Japanese Americans that carry the diplotype with no variant alleles were not different from Whites and African Americans with this diplotype, suggesting the lung cancer risk of these smokers may all be similar.