Marker expression on wildtype side population cells flow sorted and cultured for five days. Lung parenchyma, homogenized and digested with dispase, was incubated with Hoechst dye for 90 minutes in a water bath at 37°C. After washing three times with cold PBS, cells were flow sorted with the FACS ARIA cell sorter from Becton Dickinson. The sorted side population (SP) cells, gated from the typical arch formed in the scattergram by Hoechst positive cells, were kept in ex vivo culture in ES medium with LIF and assessed for markers by FCM every day for five days. Percent positive cells for markers on SP cells sorted and cultured in mouse ES medium with LIF. FACsans and flow sorts were done in triplicate per sample. *P < 0.05 compared to control, averaged from three independent experiments. Abbreviations: WS, wildtype mice treated with saline; WB, wildtype mice treated with bleomycin; d1-5, days 1 to 5 in culture.