Figure 2: Localization of cardiac resident progenitor cell populations in the human adult heart. Both side population (SP)- and c-Kit-positive cells can be found in the atrial and ventricular myocardium. In contrast, Sca1-positive progenitors are identified in the atria only. Characteristic markers for each resident population are indicated. LA, left atrium; LV, left ventricle; RA, right atrium.