These new results indicate that our original conclusion that the poor uptake of tamoxifen by sarcomas impaired recombination from the FlpO-activated CreER in Col1a1FRT-STOP-FRT-Cre-ER-T2; KrasFRT-STOP-FRT-G12D/+; p53FRT/FRT; Rosa26mTmG/+ mice is incorrect. The gene discussed is FLT1; the disease is sarcoma.