HSF1 and Protein Kinase A Figure 4. Phosphorylation at S320 influences the intracellular localization and activity of HSF1. A, B) Du145 cells with stable HSF1 knockdown were transiently transfected with either HSF1 (S320A)-GFP or HSF1 (S320D)-GFP and later heated at 43uC for 1 hour. Nuclei were detected using DAPI staining. C) Lysates from the HSF1 kd cells and control cells expressing scrambled RNA (scr) were analyzed in duplicate for HSF1 with anti- PLoS ONE | www.plosone.org 8 November 2010 | Volume 5 | Issue 11 | e13830