Previous studies have shown that ERα activation increased PI3K signalling in endothelial cells (Simoncini et al, 2000) and that RES has oestrogenic and anti-oestrogenic activities (Lu and Serrero, 1999; Bowers et al, 2000; Bhat and Pezzuto, 2001; Bhat et al, 2001) that could help explain its effects on the ERα-associated PI3K activity in MCF-7 breast tumour cells (Pozo-Guisado et al, 2004). The gene discussed is ESR1; the disease is breast neoplasm.