Fig. 1. (A) Summary of the different Gata1 mutants discussed and their outcome in terms of erythroid differentiation. FL, floxed; OX, overexpressing; KO, deleted Gata1 allele; WT, wild type. The progeny obtained in the crossing described in the present manuscript is indicated a-f, in accordance with Fig. 3A, Fig. 4C and Fig. 5A. (B) REDS signalling and erythroid differentiation. Heterotypic and homotypic cell-cell signalling mechanisms. 1 and 2 are different type of cells.