Long-term growth of ELM cells in growth factors. A total of 30 clones of ELM cells were isolated as described in Materials and Methods and transferred to wells in 96-well microtiter plates containing various growth factors and/or ECM and passaged 1:10 weekly. The viability of the clones was recorded before each passage. (A) ELM clones were transferred to wells preplated with MS5 ECM and a cocktail of growth factors added (IGF-1, IGF-2, insulin, SCF, IL-3, IL-6, IL-11, GM-CSF, and CSF1) (□). At 15 days, 50 days, and 70 days (arrows), growth factors and ECM were removed and the effect on viability of the clones monitored (▪). (B) A total of 30 ELM clones were passaged in a single growth factor (IGF-1 (◊), IGF-2 (▴), insulin (▵), SCF (▪), and IL-3 (crosses)) and clone viability monitored. (C) After clones had been maintained for 45 days in IGF-1 (◊), insulin (▵), SCF (▪), and IGF-1+SCF (□) as described in (B), they were either passaged 1:10 weekly in the same growth factors until day 155 (solid lines) or in their absence (broken lines).