TTF1 and adenocarcinoma: In addition, gain- and loss-of-function experiments in cells derived from metastatic and non-metastatic tumors demonstrate that TTF-1 controls tumor differentiation and metastatic potential in vivo.26 Another study showed that patients with adenocarcinomas with low or high TTF-1 expression had a significantly better outcome than those in which TTF-1 expression was absent.40 Tumors derived from parental A549 cells were negative for TTF-1 expression.