Figure 9.

Loss of receptor ubiquitination leads to reduced proliferation and increased apoptosis. In the presence of 1 μm PTH(7–34), HEK-293S GnTI⁻ cells stably expressing WT-PTHR or 0K-PTHR were grown at 37 °C for 72 h. PTH(7–34) was replenished every 12 h. A, cell proliferation was evaluated at 2, 24, 48, and 72 h by ELISA with bromodeoxyuridine. B, apoptosis was assessed by an ELISA that detects histones H1, H2A, H2B, H3, and H4 and an anti-DNA POD antibody that binds to single- and double-stranded DNA. n = 3 in each group; data are means ± S.D. (error bars) (**, p < 0.01; ***, p < 0.001 versus 2 h; two-way ANOVA).