Expression of MtFt in tumor xenografts and effects of MtFt expression on TfR, cytosolic ferritin levels, and RNA binding activity of IRPs. (A) MtFt expression in parental H1299 cell (H)–derived and MtFt-expressing B9 cell (B9)–derived tumor xenografts at 4 and 6 weeks after tumor injection. (B) Enhanced expression of TfR and decreased expression of cytosolic ferritin were observed in MtFt-expressing tumor xenografts. The tumor lysates were analyzed for protein expression of MtFt, TfR, cytosolic ferritin, and actin by Western blotting. (C) Increased RNA binding activity of IRPs in B9 cell–derived tumor lysates. Nine weeks after tumor cell injection, tumors were dissected and homogenized in Munro buffer. Equal amounts of tumor extracts were assayed for their ability to retard the migration of a 32P-labeled IRE probe in the absence (i) or presence of 2% β-ME (ii).
