sentence: By contrast , the nucleolar RBFs involved in more intermediate stages show distinct and more diverse extraction profiles as they can be detected in the supernatant ( SN2 ) obtained after the second fractionation step ( RRP12 ) , the SN1 and SN2 extracts ( TSR1 ) , or the SN2 and SN3 fractions ( ENP1 ) ( Fig. 1b , lanes 4 – 6 ) .