C: FACS plots from a representative experiment showing gates for purification of the cell populations. Upper left: GFP+ cells in the population of ESCs infected with pGIPZ-shRNA library lentiviruses. Upper right: Isolation of mesodermal (SSEA1-Flk1+Cxcr4-) and endodermal (SSEA1-Flk1-Cxcr4+) cells. Lower panels: Isolation of D20LS (Lin-Sca1+c-Kit-), D20LK (Lin-Sca1-c-Kit+), and D20LSK (Lin-Sca1+c-Kit+) cells. 