CDKN1B and systemic mastocytosis: Some of the targets that were up- or downregulated were also confirmed at protein level; among others, we selected two of the already known targets for miR-221, Kit and Cdkn1b[8], [24], [31], as well as one upregulated gene (Il2Ra) that is particularly relevant in mast cell biology as a marker for systemic mastocytosis [32], [33].