When SKBR3 cells were treated with NRG for 30 minutes, there is a significant increase in STAT3 phosphorylation at Tyrosine 705 (Y705) (a). Only a slight increase in STAT3 phosphorylation was seen in the presence of NRG for 10 minutes (a). When these NRG-treated cells are treated with the AG490 JAK2 inhibitor, Y705 activation is suppressed (b). The same suppression is seen when the cells are treated with the either the S3I-201 STAT3 inhibitor, or the Herceptin recombinant, humanized anti-HER2 antibody (b). In STAT3 knockdown SKBR3 cells, NRG does not affect WASF3 expression levels (c). Similarly, knockdown of JAK2 also suppresses NRG-induced expression of WASF3 (d). In the luciferase reporter assay for WASF3, NRG treatment leads to a significant increase in activity, which is suppressed in STAT3 knockdown cells (e). ChIP-qPCR assays show increased levels of STAT3 at the WASF3 promoter-binding site in the presence of NRG (f). ** p<0.01; Student’s t-test.