This exciting and highly productive Forum focused on cellular senescence – a biological response governed by known cancer-relevant pathways and thought to be integral to the suppression of cancer and the response to anti-cancer agents. Investigators from diverse areas discussed the cellular senescence mechanism from the molecular, cellular and organismal perspectives. Numerous outstanding questions were discussed including: Does senescence represent an effective mammalian tumor suppressor mechanism on one hand yet drives the age- related pathologies on the other? Are there species-specific differences in mice and humans or does this relate to experimental design? What role do telomeres plays in suppressing or fueling chromosomal instability and how does this influence the initiation and progress of cancer in the organism? What are the nature of the signals emanating from the telomere and how is this signal mediated by damage signaling pathways in normal and neoplastic cells? How is telomerase regulated? How do cellular senescence pathways influence the biological impact of oncogenic lesions such as Myc and can we forge a link to the core cell cycle machinery? A discussion of these issues generated more questions than answers and the level of discussion was so robust that most speakers found it challenging to get past the first few slides of their talk.