Endogenous expressed CD43 reduces toxicity of CD43/34 chimeras. Mast cell differentiation of wt and CD43-deficient bone marrow cells after retroviral infection with wt CD43 (top panel), CD43/34 chimera MP (middle panel), or chimera TM (bottom panel). Yields of GFP⁺/PI⁻ cells are shown in 4-day intervals up to day 36 after retroviral infection. Data are mean ± SD (n = 3) and are representative of 2 independent experiments.