JAK2V617F-induced senescence was alleviated by inactivation of the ERK2-DBP domain. (A-B) Control and JAK2V617F-transduced HSPCs (3 × 10³) derived from ERK2-WT–, -KO–, or -DBP–mutant mice were sorted and plated on M3434 (A), or M3534 methylcellulose medium (B). The number of colonies was scored 7 days after plating. The transduction of the pMIG empty vector was used as the control. Data are expressed as the mean ± standard deviation (SD). ***P < .001. (C) Control and JAK2V617F-transduced HSPCs from mice with the same genotype as in panels A and B were sorted and then cultured with IMDM supplemented with IL-3, IL-6, and stem-cell factor cytokines for 3 days. Representative images of SA-β-gal staining are depicted on the left. Percentages of SA-β-gal⁺ cells were determined by counting 100 cells in randomly selected fields from triplicate cultures. Data are expressed as the mean ± SD.***P < .001. (D-E) pMIG and JAK2V617F-transduced HSPCs from the mice above were cultured for 3 days after transduction, and then GFP⁺ cells were sorted into Trizol. The relative expression of senescence-associated and profibrotic genes was measured by real-time quantitative polymerase chain reaction. Data are expressed as the mean ± SD. All results represent ≥3 independent experiments. **P < .01; ***P < .001; ****P < .0001. IMDM, Iscove modified Dulbecco medium.