RT-PCR primers	Forward primer (5′ to 3′)	Reverse primer (5′ to 3′)	Amplified products (bps)
circMAPK1 (divergent primers)	TCAAGATCTGTGACTTTGGCCT	GGTGCTCAAAGGGGCTGATT	187
circMAPK1 (convergent primers)	ACTGCGCTTCAGACATGAGA	TGCTGAGGTGTTGTGTCTTCA	143
circ0006203	TCCCCATCACAAGAAGACCTGA	TGGTGTAGCCCTTTGGAGTCA	131
circ0008870	CAGCTAACGTTCTGCACCGT	GGTGCTCAAAGGGGCTGATT	133
MAPK1	GCACCAACCATCGAGCAAAT	CTTGAGGTCACGGTGCAGAA	179
GAPDH	GTCAAGGCTGAGAACGGGAA	AAATGAGCCCCAGCCTTCTC	158

Full material and methods were described in Additional file 4.