Effect of UV irradiation on PTHRP gene expression. Effect of UV irradiation on PTHRP gene expression. A, H-500 cells were serum starved for 24 h and were stimulated for 15 s with UVC irradiation. JNK activity was determined as described in “Materials and Methods.” These results are representative of three such determinations and are plotted as fold increase over unstimulated activity. B, H-500 cells were serum starved for 24 h and were either left untreated (0) or exposed to 40 J/m2 of UVC irradiation for 15 s. The cells were lysed at 0.5, 1, and 2 h after UVC stimulation. Fifteen μg of total cellular RNA were extracted from unstimulated and experimental cells and electrophoresed on a 1.1% agarose formaldehyde gel. After RNA transfer to nylon membranes, the filters were probed with [32P]PTHRP cDNA or with a 32P-labeled 18 S RNA probe as described in “Materials and Methods.” All blots were quantified by densitometric scanning (bottom). Results represent the three different experiments; bars, SD. ∗, significant difference from controls (P < 0.05). Fasika Aklilu et al. Cancer Res 2000;60:1753-1760 ©2000 by American Association for Cancer Research