PV EBs + DXM vs AB EBs. This comparison revealed increased activation of RTKs in PV + DXM samples, including activation of STAT3 and PDGFRβ, which are activated in both contexts but to a greater degree in PV EBs. Of interest, in the case of ND EBs, STAT3 is activated at position S727 in concordance with the activation on ATF-2 and Smad1/5/8 observed in the same cells. By contrast, PV + DXM showed activation of a broader spectrum of RTKs and downstream signaling effectors, consistent with the presence of the JAK2 V617F allele.