label: a cytidine in rRNA + S-adenosyl-L-methionine <=> an N(4)-methylcytidine in rRNA + S-adenosyl-L-homocysteine + H(+)
label_lc: a cytidine in rrna + s-adenosyl-l-methionine <=> an n(4)-methylcytidine in rrna + s-adenosyl-l-homocysteine + h(+)