The once accepted idea that LEF-1 transports β-catenin into nuclei has recently been challenged by experiments using exogenous β-catenin. Here, we investigated the effects of β-catenin and LEF-1 on nuclear import of β-catenin using different combinations of exogenous and endogenous molecules over longer lengths of time than previously studied. Nuclear β-catenin is not detectable in corneal fibroblasts and epithelia or NIH 3T3 and MDCK cells. In LEF-1 transfections, we show that the B-box of LEF-1 is required to move cytoplasmic endogenous β-catenin into the nuclei of such cells, proving that LEF-1 does transport endogenous β-catenin into nuclei. Moreover, transfection of uveal melanoma cells with B-box deficient LEF-1 inhibits nuclear import of β-catenin by endogenous LEF-1. However, the movement of overexpressed exogenous β-catenin into nuclei is unaffected by the presence or absence of LEF-1 and forms abnormal nuclear aggregates that are a prelude to subsequent apoptosis. We conclude that nuclear transport of exogenous β-catenin independently of LEF-1 has questionable physiological significance.