TRIM25 and cancer: TRIM25 has been reported to ubiquitinate a number of different substrates, possibly in some cases mediated through RNA binding,16 including RIG-I,15,17,18 DDX3X19 and ZAP,20–22 with diverse roles in immune regulation, cancer signalling pathways and antiviral activity.23–26 As such, TRIM25 is a promising candidate for redirection to a variety of neosubstrates, and the development of novel chemical tools that target TRIM25 could help to deconvolute its many proposed functions.