Abstract: The present invention relates to a method for modulating stem cells proliferation or differentiation comprising a step of contacting said stem cells with an effective amount of an activator or inhibitor of a proprotein convertase subtilisin kexin 9 (PCSK9). Inventors performed a global transcriptomic analyses in hiPSCs and showed that PCSK9 inhibition by shRNA and the intracellular PCSK9-R104C/V114A mutation negatively regulate the NODAL signaling pathway and its targets. This regulation was manifested in drastic reduction P-SMAD2/total SMAD2 protein level. This was accompanied by reduced proliferation rate where hiPSC-shPCSK9 and hiPSC-R104C/V114A demanded >1.3-fold more time to double compared to their control counterparts. They showed that PCSK9 was regulating this signaling pathway through direct physical interaction with DACT2, an intracellular attenuator of NODAL receptor and favoring its protein degradation. Thus, these findings allow to understand the differentiation and proliferation of cells.