Novel mechanism of actions whereby inhibition of TP53RK triggers anti-MM activities. H929 cells were transfected with Sc or TP53RK siRNA. Extracted mRNA was subjected to qPCR (A) and western blot (B) for RRM1. H929 cells were transfected with Sc or RRM1 siRNA. Transfectants were subjected to western blot for RRM1 (C) and viable cell count (D). H929 cells were transfected with Sc or TP53RK siRNA. Whole cell lysates were subjected to western blot (E) for p18 (CDKN2C). H929 cells were transfected with Sc or TP53RK siRNA. Extracted RNA/mRNA was subjected to GSEA for proteasome pathway (F) and qPCR for proteasome subunits (G). The cells were subjected to chymotrypsin-like proteasome activity assay (H) and western blot for ubiquitin (I). (J) H929 cells were transfected with Sc or TP53RK, followed by bortezomib (BTZ; 3 nM) treatment of 24 hours. Cell growth was assessed by MTT assay. Data represent mean ± standard deviation from triplicate cultures. Cont, control. (K) H929 cells were transfected with Sc or TP53RK siRNA and subjected to western blot. All western blots were carried out using whole cell lysates and indicated Abs.