TP53 and melanoma: In vivo, a cross-reactivity analysis of the radiolabeled mAb 125I-4H5 and 125I-7B9 (50 μg, 200 kBq) was first performed in a negative control mouse model that does not express any p53 protein with mouse melanoma B16 p53 knockout tumors (B16-KO) (Fig. 3).