label: a 5-methylcytidine in mRNA + S-adenosyl-L-homocysteine + H(+) => a cytidine in mRNA + S-adenosyl-L-methionine
label_lc: a 5-methylcytidine in mrna + s-adenosyl-l-homocysteine + h(+) => a cytidine in mrna + s-adenosyl-l-methionine