“…In mice Hematopoietic developmental pathways H Iwasaki and K Akashi carrying a green fluorescence protein (GFP) gene knocked into the Rag1 gene locus (Kuwata et al, 1999;Igarashi et al, 2001), a fraction (B5%) of LSK cells express GFP (Igarashi et al, 2002). This population, called as the earliest lymphocyte progenitor (ELP), possesses potent T-, B-and NK-differentiation potential with a weak myeloid colony-forming activity (Igarashi et al, 2002).…”