Conditional Kras G12D expression in post-GC B cells (Cγ1-Cre) and in B cells undergoing GC reaction (AID-Cre) failed to induce MM or other B cell malignancies, and only minimal B cells perturbation was induced when Kras G12D was expressed in the context of Arf pathway inactivation, a tumor-prone condition known to cooperate with Kras mutations [193]. This evidence concerns the gene KRAS and Miyoshi myopathy.