Thus, in addition to enzymatic GPI, the Gpi1 gene encodes the neurotrophic factor, neuroleukin, NK (Chaput et al., 1988; Faik et al., 1988; Mizrachi, 1989), the autocrine motility factor, AMF (Niinaka et al., 1998; Sun et al., 1999) and the maturation factor, MF, which is capable of mediating differentiation of leukaemia cells to monocytes (Xu et al., 1996). This evidence concerns the gene GPI and leukemia.