[en] After almost two decades of research, evidence suggests that transferrin receptors are rate-limiting in ⁶⁷Ga uptake. ⁶⁷Ga imaging is an in vivo detector of transferrin receptors and an indicator of tumor cell proliferation. Moreover, ⁶⁷Ga can be incorporated into tumor cells by a transferrin receptor-independent process. This pathway could be important in patients with saturated transferrin. Data that appear to support the concept that transferrin receptor-independent transporters are rate-limiting can be resolved by considering the presence of the gallate ion, [⁶⁷Ga (OH)₄]^-