Fig. 2.

Qualitative and quantitative analysis of kallikrein proteins and GAPDH in clinical FFPE tissue samples by targeted mass spectrometry. Clinical FFPE tissue samples deriving from pancreatic ductal adenocarcinoma (PDAC), non-malignant adjacent pancreas (NMAP), chronic pancreatitis (CP), normal pancreas (NP) and ampullary cancer (AMPAC) were subjected to targeted mass spectrometric analysis using parallel reaction monitoring (PRM). Samples were measured in randomized sample order. (a) Focusing on KLK6, KLK7 and KLK10 enabled the qualitative evaluation of their detectable presence or absence in the respective tissue entities. (b) Results of pairwise quantitative comparisons (two-sample t-test) between PDAC and the respective controls (NP, CP and NMAP) are illustrated as a combined volcano plot depicting KLK6 and KLK10. The log2 fold changes are plotted on the x-axis and corresponding adjusted p-values in -log10 scale are shown on the y-axis. The applied log2 fold change cut-off was set to 2-fold, while the adjusted p-value cut-off was set to 0.05 (1.3 in -log10 scale), each depicted as dashed lines. A log2 fold change > 0 corresponds to an upregulation in the PDAC condition. (c) Evaluation of GAPDH-abundance (represented as peak area) in the respective tissue entities is shown as bar plot. Error bars correspond to standard deviation.