503 cells transduced with the G-CSF receptor display enhanced survival and proliferation in the presence of G-CSF compared with parental 503 cells. After transduction with a G-CSF–expressing retrovirus, an equal number of selectable marker PLAP⁺(⧫) and PLAP⁻ (▪) 503 cells were plated in 10 ng/mL G-CSF and live cell (on the basis of trypan blue exclusion) counts monitored over 7 days. Note an almost 5-fold greater number of live PLAP⁺ versus PLAP⁻ cells after 7 days in G-CSF.