Notably, tumor onset and progression can be accelerated by co-expressing the oncogene Lmo1 or Lmo2. Tremblay and Hoang et al. have found that overexpression of Tal1 and Lmo1 resulted in a marked expansion of T-cells making up the CD4−CD8− DN1, DN3, and DN4 populations and blocked differentiation into the CD4+CD8+ double-positive (DP) stage (8). The gene discussed is TAL1; the disease is neoplasm.