label: a guanosine in mRNA + S-adenosyl-L-methionine = an N(7)-methylguanosine in mRNA + S-adenosyl-L-homocysteine
label_lc: a guanosine in mrna + s-adenosyl-l-methionine = an n(7)-methylguanosine in mrna + s-adenosyl-l-homocysteine