Fig. 1

Elevated CHEK1 expression is associated with poor outcomes in MM patients and promotes MM cell proliferation in vitro. A CHEK1 mRNA levels were significantly increased in MM samples. The signal level of CHEK1 is shown on the y-axis. Patients were designated as being healthy donors with normal bone marrow plasma cells (NP, n = 22), monoclonal gammopathy of undetermined significance (MGUS, n = 44), or multiple myeloma (MM, n = 351), and are sorted on the x-axis. B Increased CHEK1 mRNA expression was associated with poor overall survival (OS) in MM patients from the TT2 patient cohort. C Increased CHEK1 mRNA expression was associated with poor OS in MM patients from the HOVON65 cohort. D Western blot analysis revealed that CHEK1 was endogenously expressed in the specified MM cell lines. E Validation of CHEK1 overexpression (OE) in CHEK1-OE ARP1 and H929 cells relative to vehicle-transfected control cells (WT). F Four-day cell growth curve, as detected by trypan blue staining and counting of WT, CHEK1-OE ARP1, and H929 cells. G Confirmation of CHEK1 protein knockdown (KD) in ARP1 and H929 cells after transfection with three independent CHEK1-targeting shRNAs. H Four-day cell growth curve in WT, CHEK1-KD ARP1, and H929 cells. I Images of representative soft agar plates, revealing increased clonogenic growth of CHEK1-OE cells and decreased clonogenic growth in CHEK1-KD cells relative to WT. J Cell cycle analysis revealed that the proportion of G2/M phase cells significantly increased in CHEK1-OE cells relative to WT. K Cell cycle analysis revealed that the proportion of G2/M phase cells significantly decreased in CHEK1-KD cells