A water soluble vitamin B12-ReI fluorescent conjugate for cell uptake screens: use in the confirmation of cubilin in the lung cancer line A549.

A water soluble vitamin B(12)-rhenium conjugate was synthesized and used in concert with intrinsic factor to screen for cubilin receptor-mediated uptake in lung cancer cells. Internalization of the conjugate demonstrated that it could be used to rapidly screen for the cubilin receptor in living cells, subsequently confirmed with Western blotting and RT-PCR.