The remaining 44% (30/68) of tumors were heterotypic being composed of a mixture of tdTomato‐ and EGFP‐expressing neoplastic epithelial cells, indicating that multiple clones still contributed to a single tumor even when at least one clone expressed the Pik3ca* transgene prior to tumor initiation (Figure 4(A–D)). The gene discussed is PIK3CA; the disease is neoplasm.