Different expression level of RNase P protein subunits after disruption of Rpp38 in HeLa cells. Five hundred nanograms (A), 100 ng (B), 10 ng (C), and 0.1 ng (D) of cDNA corresponding to Rpp14 (lane 1), Rpp20 (lane 2), Rpp21 (lane 3), Rpp25 (lane 4), Rpp29 (lane 5), Rpp30 (lane 6), Rpp38 (lane 7), Rpp40 (lane 8), hPop1 (lane9), hPop5 (lane 10), β-actin (lane 11), and H1 RNA transcribed in vitro (lane 12) were dotted on nitrocellulose filters, cross-linked with Stratagene Stratalinker, and hybridized with labeled cDNA probe. To obtain the labeled cDNA probe, one 150-mm plate of HeLa cells transfected with 20 μg of pmU6-EGSRpp38-TL or pmU6-EGSRpp38 plasmid was then harvested 24 h posttransfection. Total RNA purified from these cells was used in the reverse transcription reaction. cDNA obtained from this reaction was labeled with [α-32P]dCTP.