ATRA-induced differentiation of HL-60 cells was studied using targeted mass-spectrometry including selected reaction monitoring (SRM) and parallel reaction monitoring (PRM) approach. PRM experiment was performed in time-course manner, without peptide standards usage. PRM data was inspected in Skyline 3.1 software. In order to check peptide identity we developed spectrum library based on shotgun mass-spectrometry data, which has been obtained for HL-60 cells protein samples at 0, 3, 24, 48 and 96h after ATRA treatment.