Figure 6.
Presence of p21 and its binding partner, PCNA, in APBs. (A) Double immunostaining of TRF1 and p21 in C7 cells treated with 4OHT for 1 d, C8 cells treated with 4OHT for 4 d, and IIICF-T/B3 cells treated with a combination of SV40T and control siRNAs for 4 d. p21 was detected inside APBs. (B) Triple immunostaining of TRF1, p21, and PCNA in IIICF-T/B3 cells treated with a combination of SV40T and control siRNAs for 3 d. p21 and PCNA were colocalized in APBs. (C) The effectiveness of PCNA siRNAs (PCNA-1 and PCNA-6) was demonstrated by Western blots. (D) Triple staining of TRF1, SV40T, and PCNA in IIICF-T/B3 cells treated with combination of SV40T and PCNA-6 siRNAs for 4 d. APBs were still detected in cells depleted of both SV40T and PCNA. Bars, 20 µm.