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