IFNα differentially impacts on JAK2^V617F and CALR^m HSC homeostasis. (A) Graphs indicate the means values (solid lines) of the estimated parameters calculated using the mathematic model. (i) Δ* parameters were calculated in heterozygous and homozygous JAK2^V617F HSCs and heterozygous CALR^m HSCs. Δ*_het significantly differs in patients with CALR^m MPN vs those having JAK2^V617F MPN (Mann-Whitney U test, P = .0031). Δ*_het in patients with CALR^m MPN is significantly different from Δ*_hom of those having JAK2^V617F MPN (Mann-Whitney U test, P < .0001). The dotted lines indicate Δ* = 0. Δ* > 0 corresponds to an expansion, and Δ* < 0 corresponds to a depletion of the stem compartment. (ii) Δ*_het parameters were calculated in type 1 and type 2 CALR^m HSCs. Δ*_het significantly differs in patients with type 1 CALR^m MPN vs those with type 2 CALR^m MPN (Mann-Whitney U test, P = .004). (iii) Inverse ratios of the ɣ* parameter was calculated in heterozygous vs homozygous JAK2^V617F HSCs. The 1/ɣ* value can be seen as a relative time spent by cells in the inactive compartment of our model. The 1/ɣ* significantly differs in heterozygous vs homozygous JAK2^V617F HSCs (Mann-Whitney U test, P = .027). (B) Proposed mechanism of IFNα in JAK2^V617F and CALR^m HSCs.