Here, we show that the ubiquitously-expressed PI3Kα and PI3Kβ class I PI3K isoforms, and an associated signalling network, regulate primary cilia disassembly in cells, development and cancer, and speculate that diseases caused by aberrant PI3Kα-activation may be considered as a DCC, a subset of ciliopathies in which some of the clinical manifestations result from cilia dysfunction. The gene discussed is PIK3CA; the disease is cancer.