Instead of HF itself, some authors have suggested there is a tendency to list the underlying cause of the HF, or another cardiac condition, in the primary position of the hospital discharge summary. Other assays to monitor ER stress include: placement of a reporter, such as LacZ, GFP or luciferase under the Picroside-II control of an ER stress response element; spliced activation of an XBP-1-venus fusion protein; and Taltirelin changes in rates of SEAP secretion. In this study, we describe a simple, highly sensitive assay for monitoring both the secretory pathway and ER stress in living mammalian cells based on expression of the naturally secreted Gluc and monitoring release of luciferase activity in real-time. Parameters of Gluc secretion were monitored in cultured cells including linearity of release with time and cell number and response to drugs that either interfere with the secretory pathway or induce ER stress. We have previously shown that detergent resistant membranes can be isolated from late endosomes purified from baby hamster kidney cells using a well-established subcellular fractionation protocol. These DRMs were found to contain well-characterized raft marker proteins such as GPI-anchored proteins and flotillin-1 but were devoid of the transmembrane glycoprotein lamp1 and the lipid anchored GTPase Rab7. It is important to note that since detergent solubilization was performed on a purified organelle obtained in a relatively low abundance, the detergent to protein ratio used was five to ten times higher, for technical reasons, than that routinely used by us and other on whole cell extracts. Thus the obtained membranes are highly detergent resistant. To test whether late endosomal DRMs are sensitive to cholesterol affecting drugs, an important criterion for being a raft-like domain, we treated late endosomes with either the cholesterol clustering agent saponin or the cholesterol binding compound filipin. We did not perform cholesterol extractions using ?-methyl-cyclodextrin, a drug commonly used to disrupt rafts, since we have previously shown that on BHK cells this treatment does not to lead the release of GPI-anchored proteins from DRMs.