Embryonic stem (ES) and induced pluripotent stem (iPS) cells respond to a variety of growth factors that are important regulators of pluripotency. For example, ES and iPS cells can be maintained in an undifferentiated state in vitro
when grown in conditioned media supplemented with proteins such as fibroblast growth factor (FGF). Other growth factors, including members of the Growth/Differentiation Factor (GDF) and Wnt families, are thought to induce the differentiation of ES and iPS cells into a variety of somatic cell types. Elucidating the growth factor signaling pathways that regulate ES and iPS cell pluripotency and differentiation are important for understanding normal development and establishing disease models.