PTGS2 and cancer: Furthermore, strong correlations of PTGS2 or PTGES and EGR1 mRNA levels in several cancer datasets were found, and particularly in Skrzypczak Colorectal 2 dataset, Pearson's correlation was 0.84 for PTGS2 and EGR1 and 0.647 for PTGES and EGR1 mRNA levels (Table 2).