The distribution of MR1-1-PE38KDEL at a concentration of 25 ng/mL by CED was monitored by coinfusion with the low molecular weight tracer gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) and 124I-labeled human serum albumin in a malignant glioma patient [122]. The gene discussed is MR1; the disease is malignant glioma.