TP53RK is upregulated in MM patients with poor prognosis and MM cell lines. (A) Comparative GEP analysis of TP53RK between normal plasma cell (PC) and MM cells. (B) Overall survival relative to TP53RK expression in patients with newly diagnosed MM (log-rank test). (C) Whole cell lysates from MM cell lines (1: MM.1S, 2: H929, 3: OPM1, 4: KMS11, 5: RPMI8226, 6: U266, 7: doxorubicin-40 (Dox-40), 8: OPM2) were subjected to western blot. (D) MM.1S cells were infected with control (Luc) or TP53RK (1, 2) shRNAs. After puromycin selection, cells were cultured for 72 hours and growth was assessed by MTT assay. (E) H929 cells were transfected with scrambled (Sc) or TP53RK siRNAs. After transfection, cells were cultured for 72 hours and growth was assessed by MTT assay. (F) H929 cells were transfected with control, wt, or TP53RK kinase-dead mutant (D163A), and viable cells enumerated by trypan blue. (G, H) H929 cells were cotransfected with wt-TP53RK and/or TP53RK siRNA. 1: vector control + Sc siRNA, 2: vector control + TP53RK siRNA, 3: wt-TP53RK + Sc siRNA, 4: wt-TP53RK + TP53RK siRNA. Cell growth and TP53RK protein expression were assessed by MTT assay (G) and western blot (H), respectively. ImageJ was used for densitometric analysis. (I) TP53RK was knocked down in MM.1S cells. Whole cell lysates from MM cells were subjected to western blot with indicated Abs. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-dimethyltetrazolium bromide.