Proliferating cells can be traced exploiting expression of KI67. KI67 is restricted to all cell-cycle phases except G0. A KI67-expression controlled Cre-recombinase can be used to trace dividing cells to assess their long-term clonogenicity and multipotency. When reporter recombination is initiated in a dividing stem cell (labeled in red, first scenario), long-term tracing will be observed. When the dividing cell is a committed progenitor, labeling is transient and will eventually be lost (second scenario).
