Figure 1c–e shows that reduction of SP1 mRNA and protein levels in CLL cells using specific siRNA results in a concomitant reduction of PKCβII mRNA and protein expression. Similar reduction of SP1 and PKCβII mRNA was observed using MEC1 cells, with optimal results being obtained using a mixture of SP1-specific siRNA oligonucleotides (Supplementary Figure 1B,C). The gene discussed is SP1; the disease is B-cell chronic lymphocytic leukemia.