Fig. 1

Identification and characteristics of circMAPK1 in GC. a The number of MAPK pathway-related circRNAs in human cell lines. b The expression of hsa_circ_0004872, hsa_circ_0006203 and hsa_circ_0008870 in the 40 paired GC and adjacent tissues by qRT-PCR. c Circular junction reads of hsa_circ_0004872 in normal and cancerous cells/tissues from Jeck2013, Salzman2013 and Rybak2015 studies in circBase. Normal cells/tissues include parietal lobe, temporal lobe, diencephalon, occipital lobe, frontal cortex, cerebellum, Hs68 RNase, A549, Ag04450, Bj, Gm12878. Cancerous cells/tissues include Helas3, Hepg2, Huvec, K562, Mcf7, Nhek, Sknshra. d The normalized expression of hsa_circ_0004872 in GSE100170 database and GSE121445 database. e The schematic diagram of circMAPK1 (hsa_circ_0004872) arose from exon 2,3,4 of the MAPK1 gene. f Sanger sequencing was conducted to confirm head-to-tail splicing. g The expression level of circMAPK1 in a series of cultured GC cell lines (GES-1, HGC27, MGC803, MKN45, BGC823, SGC7901, AGS) was analyzed by real-time PCR. h The divergent primers detected circMAPK1 in cDNA but not in gDNA, GAPDH was used as a negative control. i In SGC7901 and MGC803 cells treated with Actinomycin D, relative RNA levels of circMAPK1 and MAPK1 mRNA were measured in different time points. j Real-time PCR analysis of circMAPK1 and linear MAPK1 mRNA after treatment with RNase R in SGC7901 and MGC803 cells showed that circMAPK1 was resistant to RNase R treatment. k The nuclear mass separation assay and l FISH showed that the sub-cellular distribution of circMAPK1 was mostly present in the cytoplasm. m Relative circMAPK1 expression in additional 80 paired GC and adjacent tissues. N Overall survival analysis based on circMAPK1 expression in 80 GC patients. Graph represents mean ± SD; *p < 0.05, **p < 0.01, and ***p < 0.001