Cytokine independence and constitutive activation of signaling pathways in Ba/F3 cells. (A) Kinase alterations investigated in this study. Red and yellow shapes denote sequence mutations. (B) Growth of Ba/F3 cells in the absence of IL-3. Cell number was determined using trypan blue. Each point represents the mean ± standard deviation (SD; n = 3). (C) Phosphoflow cytometric analysis of signaling phosphoproteins in Ba/F3 cells. Cells were grown in the absence of IL-3, harvested, and assessed for the phosphorylation of pSTAT5, pCRKL, pERK1/2, and PS6. A-J, ATF7IP-JAK2; E-N, ETV6-NTRK3; KD, kinase domain; M-I, MYH9-IL2RB; P-A, PAG1-ABL2; P-J, PAX5-JAK2; R-A, RCSD1-ABL1; R-ABL2, RCSD1-ABL2; RAN-A, RANBP2-ABL1; S-C, SSBP2-CSF1R; Z-A, ZMIZ1-ABL1.