SPP1 and neoplasm: However, upon transfection of an expression vector for AGR2 into parental Rama 37 cells and their transplantation into syngeneic rats, the primary tumours appear on average with an increased latency compared to that for S100A4-transfected, osteopontin-transfected or the parental Rama 37 cells (Davies et al, 1993; Oates et al, 1996; Liu et al, 2005).