TIPARP and prostate cancer: To determine which ADP-ribosyl-Cys sites are responsible for PARP7-mediated AR degradation, we used a panel of ten AR mutants with amino acid substitutions (Gly, Ser) for Cys sites shown by mass spectrometry (Yang et al, 2021) to undergo androgen-induced ADP ribosylation in prostate cancer cells (Fig. 6A–F; Appendix Fig. S5A–G; Appendix Table S4).