Transduction of PU.1 into PU.1-deficient cells restores G- and M-CSF receptor expression. (A) PU.1- and M-CSF receptor transduced cells (503-PU, 503-MR) that were selected by PLAP expression or growth in M-CSF, respectively, were analyzed by RT-PCR. M-CSF receptor mRNA was evident in normal macrophages (MAC), 503-PU, and 503-MR. These primers were intron-crossing, and controls for DNA amplification in the absence of RT that were also performed were negative (not shown). The far lefthand lane contains a 100-bp DNA ladder. (B) Whole-cell lysates were prepared and 25 μg of total cellular protein was separated by SDS-PAGE. After blotting and probing with polyclonal anti–G-CSF receptor antibody, G-CSF receptor protein was detectable in G-CSF receptor- and PU.1-transduced 503 cells (503-GR, 503-PU) and normal neutrophils, but not in 503 cells or the B cell line A20-2J. The lane labeled MW contains protein size standards (CruzMarker; Santa Cruz Biotechnology).