In line with this hypothesis, we recently showed that compared to other FGFR3 recurrent mutations, the higher prevalence of FGFR3 S249C mutation (one of the most common mutations in bladder cancer) was likely due to an increased mutation rate induced by APOBEC, rather than selection related to an increased tumorigenicity of this mutation [4–6]. The gene discussed is FGFR3; the disease is urinary bladder cancer.