Figure 6.
The OGF–OGFr axis in RTCFs inhibits DNA synthesis and requires the presence of both p16 and p21 pathways. (A) RTCFs were transfected for 24 hours with p16, p21, or scrambled siRNA, and total proteins were isolated 48 hours after transfection, separated by SDS-PAGE, and probed with antibodies specific to p16 or p21 to demonstrate level of protein knockdown. (B) Densitometric analysis of three Western blot analyses from independent experiments was performed, and p16 and p21 expression (% p16/actin and p21/actin ratio) is expressed relative to nontransfected cultures. (C) p16 and p21 pathways are necessary for OGF's inhibitory action on cell proliferation. RTCFs were transfected with p16, p21, p16 and p21, or scrambled siRNA for 24 hours and subsequently treated with 10−6 M OGF or an equivalent volume of sterile water for 72 hours. Data represent the mean ± SE cell counts for at least two aliquots/well and at least two wells/treatment. Significantly different from wild-type cultures as well as those transfected with scrambled siRNA at **P < 0.01 and ***P < 0.001.