Fig. 2

MPP1 promotes hematopoietic progenitor cell (HPC) replating and only requires the PDZ domain to bind ABCC4. a (left panel) HPC were transduced with retroviral plasmids containing cDNAs for either MPP1-ires-CFP or MYCN-ires-YFP, purified by FAC sorting and plated in methycellulose medium containing IL3, IL6, SCF, and EPO. Colonies were counted after 7 days growth and serially replated (right panel). HPC from either Abcc4^+/+ or Abcc4^−/− were transduced with MPP1 as described above, FAC sorted and replated in methylcellulose serially. b Immunoblot analysis of lysates from the AML cell line MO7e following immunoprecipitation of either ABCC4 or MPP1. SN supernatant. IP immunoprecipate. c ABCC4 expression plasmids either containing the PDZ motif or lacking the PDZ-motif (ABCC4ΔC) with an MPP1 expression vector. d Diagram depicting the protein domains of MPP1. e Coomassie-stained polyacrylamide gel of purified full-length MPP1 and purified sub-domains. f Incubation of purified MPP1 fragments with MO7e lysates, followed by immunoprecipitation and probing the immunoprecipitate with an antibody against ABCC4 (n = 3, bars represent SEM). g A proximity-ligation assay shows ABCC4 and MPP1 interact in MO7e cells (red). Experiments were replicated three times; bars represent SEM