Fig. 4

Logistic Regression analysis determines transcription factor binding motif enrichment for XBP1 and ATF6. a Interaction network adapted from the STRING database showing the immediate network neighborhood of the two enriched transcription factors ATF6 and XBP1 obtained through the analysis described in Table 1. Big nodes indicate input genes, red nodes indicate increased expression, green nodes indicate decreased expression as identified in the microarray analysis described in Fig. 2. Grey nodes are part of the interaction network but were not identified in the microarray results. b MCF7 and SKBR3 cells were transfected with the transcriptional reporter construct pCAX-XBP1-ΔDBD-venus which results in the expression of a functional fluorescent XBP1-venus fusion protein after mRNA splicing by the ER stress regulator IRE1. STF803010 inhibits the RNase activity of IRE1 (+ = 10 μM). The cells were treated with 250 μM palmitate 24 h post-transfection, alone or in combination with STF803010 and green fluorescent cells were counted using the InCell Analyzer 2200. C16 = palmitate. The data were normalized to control conditions and are presented as mean ± SD. ** = p · 0.01, One-way ANOVA with Bonferroni post-test. n = 3