Fhit-negative H1299 lung cancer cells carrying an inducible FHIT cDNA (D1 cells; refs. 27) were treated with the inducer, Ponasterone A (Pon A), for 48 h and indirect immunofluorescence detection of Fhit subcellular location was assessed using anti-Fhit serum and MitoTracker red 580, a mitochondria marker; Fhit fluorescent signal (green staining, Fig. 1a) was cytoplasmic and partly co-localized (yellow staining, Fig. 1a, lower right) with MitoTracker Red dye, indicating that exogenous Fhit localized to the mitochondria and cytosol. The gene discussed is FHIT; the disease is lung carcinoma.