A proteomics approach was used to identify the phosphorylated
proteins whose phosphorylated levels were affected by Notch
signaling in the LPS-activated macrophage cell line, RAW264.7. Pretreatment
with GSI and DAPT, was carried out before stimulation
with LPS. One of the proteins that were identified in this study was RGS19 (Supplementary data: Figures S1 and S2). As shown in Fig. 1,
the levels of total RGS19 after separation by 2D-GE were similar in
cells treated with the vehicle control (DMSO) or DAPT. However,
the phosphorylation level, as detected by Pro-Q® Diamond phosphoprotein
staining, in DAPT-treated cells were lower than that
of the control. The effectiveness in inhibiting the processing of the
Notch receptor by DAPT was verified by decreased levels of cleaved
Notch1 (Val1744)