Figure 4

Signal transducer and activator of transcription 3 (Stat3) activation is through the interleukin-6/glycoprotein 130/Janus kinase (IL-6/gp130/Jak) pathway. (a) Nuclear extracts isolated from MDA-MB-468 (468) cells treated with immunoglobulin G (IgG) (10 μg/ml), P6 (1 μM), BR3 (10 μg/ml), and α-IL-6 (1 μg/ml) for 16 hours were analyzed for tyrosine-phosphorylated Stat3 (pStat3) and total Stat3 protein. (b) Nuclear extracts isolated from MDA-MB-231 (231) cells treated with IgG (10 μg/ml), P6 (1 μM), BR3 (10 μg/ml), and α-IL-6 (1 μg/ml) for 16 hours were analyzed for pStat3 and total Stat3. (c) Nuclear extracts isolated from MDA-MB-435 (435) cells treated with IgG (10 μg/ml), P6 (1 μM), and BR3 (10 μg/ml) for 16 hours were analyzed for pStat3 and total Stat3. (d) Nuclear extracts isolated from 4175 and 231 cells treated with IgG (10 μg/ml) and BR3 (10 μg/ml) for 16 hours were analyzed for pStat3 and total Stat3. (e) Nuclear extracts isolated from MCF10A cells treated for 30 minutes with conditioned media (CM) from MDA-MB-468 cells after pretreatment for 4 hours with IgG control antibody, BR3 (5 μg/ml), α-IL-6 antibody (5 μg/ml), α-oncostatin M (OSM) antibody (10 μg/ml), and α-leukemia inhibitory factor (LIF) antibody (10 μg/ml) were analyzed for pStat3 and total Stat3.