FISH analysis of Hone1 derived cells. A. Dual-color metaphase FISH (see METHODS) shows that in Hone1, parts of chr3 detected by chr3 painting probe (green) are included into different marker chromosomes (M1, M2 ...). The four underlined markers contain 3p21 as determined using the RP6-123I13 probe (red). B. After chromosome transfer, two additional normal chrs3 (N) are detected in #3/HONE1, clone 1. C. Identification of the marker chromosomes by four-probe metaphase FISH (see METHODS). Chr2, 3 and 12 painted parts are shown in red, blue and yellow, respectively. 3p21 RP6-123I13 signal is green. M1 has a translocation of a part of chr12. M2 carries a chr2 insertion. In M5, chr3 parts are translocated to a chr12 derived segment. D. Interphase FISH shows six RP6-123I13 probe signals (red) in the majority of the #3/Hone1 nuclei (blue DAPI staining). The sample was taken at the zero time point of in vitro propagation. This implies that the sample carries two supernumerary copies of the 3p21 (CER1) region, compared to four copies characteristic for Hone1. E. Interphase FISH, using the same probe, shows that #3/Hone1 cells have lost two supernumerary 3p21 copies after in vivo growth (tumor 2).