Transformed B-lymphoid cells have escaped growth suppression by JunB. (A-B) Three clonal populations of v-abl-transformed pro-B cell lines (termed 26, 27, and 47) were cocultivated with retroviral JunB-producer cell lines for 48 hours and subsequently subjected to a [3H]thymidine proliferation assay (A) or cloned in cytokine-free methylcellulose (B). Data represent means ± SE from 6 individual wells or 4 individual plates. (C) Western blot analysis of the 3 cell lines infected with pB-junB. Mock-infected cells were used as controls. (D) Induction of JunB by UV irradiation in 4 different v-abl-transformed cell lines expressing various expression levels of p16. Western blot analysis of JunB, p16, and β-actin. (E) Injection of v-abl-transformed cells in nude mice caused tumor formation in 72% of the JunB transgenic cells and in 67% of the wild-type cells. Shown are tumor weights 2 weeks after injection. Data represent means ± SE from 6 individual wells (A) or 4 individual plates (B).