1x96-well filter plate, x-Plex assay format that includes premixed coupled beads, detection antibodies, and lysates for detecting phosphorylated p53 (Ser46), p70 S6 kinase (Thr421/Ser424), p90RSK (Thr359/Ser363), PDGF receptor-β (Tyr751), requires phosphoprotein reagent and cell lysis kit offered separately