The Unfolded Protein Response (UPR) is a conserved and essential stress response that cells activate to combat endoplasmic reticulum (ER) stress, commonly caused by the accumulation of misfolded proteins or failing protein quality control. ER stress is a well-characterized feature of several diseases, such as diabetes, Alzheimer's, Parkinson's, Huntingon's, and prion diseases. Early cellular response to ER stress includes the transcriptional upregulation of chaperone proteins, which is mediated by a large number of transcription factors (TFs). Signosis has developed the FewCell ER Stress/UPR TF Activation Profiling Plate Array, which can be used to simultaneously monitor 16 ER stress/UPR related TFs, including XBP-1, ATF4, ATF6, GADD153/CHOP, CBF/NFY, SREBP1, YY1, PGC-1a, ATF3, AP-1, FOXO1, IRF, p53, NFkB, NRF2/ARE, and HNF4. The array requires as few as 2,000 cells and the cellular protein is extracted with one-step procedure using the whole cell lysis buffer. The Kit contains one plate which can be used for 6 assays.