Fig. 2

Fluorescence microscopy images of different cell lines at different passages. C25-young cells remain in an oligoclonal state until passage 23, which cannot be assessed in fluorescence microscopy. Note overgrowth of one or two colours in both C25-old and BJ cell lines. In C25-old cells, a mix of a grey/blue and a purple clone can be detected; while in BJ cells, a single clone of yellow/gold colour has almost overtaken the cell culture. Decrease in colour diversity detected from passage 23/24 onwards. C25-young cells stay in oligoclonal state until passage 23 which cannot be deduced from these microscopic images (compare Fig. 1). Scale bar indicates 200 nm. p passage