Lineage-specific promoters express specifically in MK and HSCs in vivo. (A) Self-inactivating (SIN) lentiviral vectors harboring lineage-specific internal promoter fragments (IP) for expression of eGFP or HA-Mpl. SD indicates splice donor; SA, splice acceptor; ψ, packaging signal; RRE, rev responsive element; and PPT, polypurine tract. (B) Relative expression of lineage-specific promoters in different immature and committed BM progenitor populations compared with the ubiquitously expressing PGK promoter. Mean fluorescence intensity of eGFP-positive cells was divided by the mean fluorescence intensity of the PGK promoter. (C) Representative eGFP expression from lineage-specific promoters in platelets and red blood cells (RBC). Percentage of eGFP-positive cells indicated. (D) Expression of lineage-specific promoters in other mature lineages of the BM. CD11b/Gr1 indicates granulocytes and monocytes; CD19, B cells; CD3, T cells; and Ter119, erythroid progenitors. Percentage of positive cells indicated.