It is likely that homozygosity, but not heterozygosity, of K74R substitution causes one or more types of the hematopoietic cells to gain new functions, such as the higher cancer cell-killing capability of NK(K74R) cells (Figure 6).The data of Figure 2D further suggest that the amount of specific types of cells such as NK(K74R) in the 20% of blood cells carrying homozygous Klf1(K74R) alleles in the recipient mice upon BMT is sufficient to confer the mice a higher anti-cancer ability. Here, KLF1 is linked to cancer.