p193/CUL7 is an E3 ubiquitin ligase initially identified as an SV40 Large T 
Antigen binding protein. Expression of a dominant interfering variant of mouse 
p193/CUL7 (designated 1152stop) conferred resistance to MG132- and 
etoposide-induced apoptosis in U2OS cells. Immune precipitation/Western analyses 
revealed that endogenous p193/CUL7 formed a complex with Parc (a recently 
identified parkin-like ubiquitin ligase) and p53. Apoptosis resistance did not 
result from 1152stop-mediated disruption of the endogenous p193/CUL7 binding 
partners. Moreover, 1152stop molecule did not directly bind to endogenous 
p193/CUL7, Parc or p53. These data suggested a role for p193/CUL7 in the 
regulation of apoptosis independently of p53 and Parc activity.