Cytoplasmic nucleoside kinases regulate mtDNA levels. DCK (A), TK1 (B), CMPK1 (C), and TFAM (D) were knocked down with shRNA in TEX and OCI-AML2 cells as described in “Materials and methods.” After target knockdown, mtDNA content was assessed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) using primers for mt-ND1 relative to nuclear-encoded HGB. Immunoblots are displayed in supplemental Figure 3. Data are shown as mean ± standard deviation (SD) of 3 independent experiments. *P < .05, **P < .01, ***P < .001, and ****P < .0001 using the Bonferroni posttest after 1-way ANOVA. NS, not significant.