Imatinib treatment of murine EL4 tumors impaired growth, decreased pericyte coverage, and reduced vascularization. (A) Tumor weight (g) at the time of tissue harvest, comparing imatinib (red) vs PBS (black). (B) Analysis of pericytes with (1-2) NG2, (3-4) PDGFRβ, and (5-6) α-SMA staining, and CD31⁺ vessels in EL4 tumors, in response to either imatinib or PBS. (C) Microvessel density was quantified as CD31⁺ staining density, and normalized to the PBS control. Pericyte coverage was quantified as NG2⁺, PDGFRβ⁺, or α-SMA⁺ area and normalized to the PBS control. *P < .05. Scale bar, 50 μm.