MYC and systemic lupus erythematosus: In contrast to the observed normal BM B cell development in Cd19Cre/+ mice in most studies, two groups reported a reduced pre-B cell compartment in lupus-prone (NZB x NZW) F1 mice or Eμ-Myc C57BL/6 mice (overexpressing the c-Myc transgene under control of the immunoglobulin heavy chain gene enhancer Eμ) [19,21].