TGFB1 and sarcomatoid carcinoma: While TGFβ1 transgenic mice develop spindle cell carcinomas demonstrating EMT, tumors from bigenic mice that overexpress both TGFβ1 and dominant-negative TβRII do not, which demonstrates that TGFβ signaling in the epithelial cells is required for EMT, while induction of invasion and metastasis is not [149].