Abstract

The Wnt family of developmental regulators were named after the Drosophila segmentation gene wingless and the murine proto‐oncogene int‐1. Homology between these two genes connected oncogenesis to cell‐cell signals in development. I review how wingless was initially characterized, and cloned, as part of the quest to identify developmental cell‐to‐cell signals, based on predictions of the Positional Information Model, and on the properties of homeotic and segmentation gene mutants. The requirements and cell‐nonautonomy of wingless in patterning multiple embryonic and adult structures solidified its status as a candidate signaling molecule. The physical location of wingless mutations and transcription unit defined the gene and its developmental transcription pattern. When the Drosophila homolog of int‐1 was then isolated, and predicted to encode a secreted proto‐oncogene homolog, it's identity to the wingless gene confirmed that a developmental cell‐cell signal had been identified and connected cancer to development.