The sequence complementarity between HIV-1 5' splice site SD4 and U1 snRNA determines the steady-state level of an unstable env pre-mRNA.
S Kammler, C Leurs, M Freund, J Krummheuer, K Seidel, T O Tange, M K Lund, J Kjems, A Scheid, and H Schaal
RNA. 2001 March; 7(3): 421–434. PMCID: PMC1370098