Early dominance of TET2 mutations contributes to granulomonocytic skewing in CMML. (A) Correlation between the proportion of TET2-mutated clones of CD34⁺/CD38⁻ cells grown in liquid culture with cytokines with (n = 11) or without (n = 2) a stromal layer (top panel), or corresponding CD34⁺/CD38⁺ cells grown in methylcellulose (n = 11) or in liquid culture (n = 2; bottom panel) from 13 TET2-mutated samples (8 MPN, 5 MDS). Spearman test and slope from linear regression. (B) Percentage of CMP clones with mutated TET2 assessed in liquid culture (gray bars) compared with the percentage of granulomonocytic colonies after methylcellulose culture of CMP in the presence of SCF, IL-3, G-CSF, and EPO (black bars). Results are from 5 samples. Numbers on top of the gray bars indicate the number of CMP clones assessed. UPN: unique patient number. (C) Sorted CD34⁺/CD38⁻ and CD34⁺/CD38⁺ cord blood cells were transduced with an shRNA directed against TET2 or a scrambled shRNA (as previously described²³ ). After infection, GFP⁺ cells were cultured as in (B). At day 14, cells were washed and stained with PE-anti-GPA and APC-anti-CD33. Ratios of GFP⁺ granulomonocytic (CD33⁺/GPA⁻) to erythroid (CD33^±/GPA⁺) cells from 4 independent experiments are represented (mean ± SEM, Mann-Whitney U test, *P < .05).