TGFBR1 and neoplasm: In agreement with this assumption, upon orthotopic transplantation of individual PANC-1 clones stably expressing kinase-active ALK5 (ALK5T204D) into immunodeficient mice, this mutant, but not the Smad binding-defective derivative of ALK5T204D (RImL45T204D) greatly reduced tumor size but induced the formation of liver metastases in otherwise non-metastatic PANC-1 cells.