Our investigation of the transcriptional dynamics of the PDE4D gene locus revealed a previously undescribed promoter switch involving the major contributors of PDE4D activity in normal prostate, namely the PDE4D5 and PDE4D9 long forms, as well as the prostate cancer-associated long isoform PDE4D7 [15, 16]. The gene discussed is PDE4D; the disease is prostate carcinoma.