Structure−Activity Relationships in 1,4-Benzodioxan-Related Compounds. 8. 1 {2-[2-(4-Chlorobenzyloxy)phenoxy]ethyl}-[2-(2,6-dimethoxyphenoxy)ethyl]amine (Clopenphendioxan) as a Tool to Highlight the Involvement of α 1D - and α 1B -Adrenoreceptor Subtypes in the Regulation of Human PC-3 Prostate Cancer Cell Apoptosis and Proliferation