Fig. 5. Expression of Mi products by immunofluorescence in LE-mi-transfected QNR cells. A, after G418-selection, some of the LE-mi-QNR foci were pigmented (b and d), in contrast of the LE-QNR foci (a and c). a and b, cells were fixed in 4% PFA in PBS. Pigmented foci were clearly visible. c and d, cells were stained with Coomassie Blue to visualize pigmented and nonpigmented foci. B: a, nuclei were stained with Hoescht 33258 in PBS. b, subcellular localization of Mi was assayed by indirect immunofluorescence on fixed QNR cells with serum MiC. Anti-Mi-immunoreactive proteins were detected with FITC-labeled swine antirabbit immunoglobulins secondary reagent. c, pigment cells were observed by direct light microscopy. Nuclei were labeled in pigmented LE-mi-QNR cells (arrows) but not in nonpigmented cells (arrowheads). C: a, LE-mi-QNR nuclei were stained with Hoescht 33258 in PBS. b, TUNEL assay. DNA of fixed cells is labeled by the addition of fluorescein dUTP at strand breaks by terminal transferase (arrow). c, pigment cells were observed by direct light microscopy. d, LE-QNR nuclei were stained with Hoescht 33258 in PBS. e, TUNEL assay. f, cells were observed by direct light microscopy (no pigment found).