ISL1 and myxoma: ,21,24 Immunofluorescent staining revealed that c-kitpos/CD45neg/CD31neg myxoma cells co-express several stemness and cardiac progenitor cell transcription factors, such as Oct-4, Nkx2.5, and Isl-1 in different percentages (Figure  1F–I), markers known to be also expressed in normal c-kitpos/CD45neg/CD31neg CSCs from healthy human atrial tissue.23