CXCR4 and neoplasm: Co- injection of 50 μg cyclo-(-d-Tyr 1-Arg 2-Arg 3-Nal 4-Gly 5) or AMD3100 (data not shown) per mouse significantly reduced the tumor uptake, thus demonstrating specificity of CXCR4-mediated tumor binding or [68Ga]2 c.