Cancer cells have the ability to divide indefinitely and spread to different parts of the body during metastasis. Embryonic stem cells can self-renew and, through differentiation to somatic cells, provide the building blocks of the human body. Embryonic stem cells offer tremendous opportunities for regenerative medicine and serve as an excellent model system to study early human development. Many of the molecular mechanism underlying tumorigenesis in cancer and self-renewal in stem cells have been elucidated in the past decade. Here we present a systematic analysis of seven major signaling pathways implicated in both cancer and stem cells. We present on overview of the JAK/STAT, Notch, MAPK/ERK, PI3K/AKT, NF-kB, Wnt and TGF-beta pathways and analyze their activation status in the context of cancer and stem cells. We focus on their role in stem cell self-renewal and development and identify key molecules, whose aberrant expression has been associated with malignant phenotypes. We conclude by presenting a map of the signaling networks involved in cancer and embryonic stem cells.