CAMK2 inhibitors were identified by the compound screening using MF-iPS cells established with episomal vectors. (A) Three rounds of the compound screening were performed with 188 compounds, including kinase inhibitors, genotoxic agents, and neurotransmitter inhibitors at 3 different concentrations. (B) The first screening was performed with MF-iPSCs harboring JAK2 V617F. After choosing 17compounds, the second screening was performed with MF-iPSCs harboring CALR type 1 mutation. After 3 rounds of screening, KN-93 (CAMK2 inhibitor) was identified as a therapeutic compound. (C) Results of the screening of KN-93 for all 3 MF-IPSCs are shown. (D) TFP, another CAMK2 inhibitor, was used to validate the effectiveness against all 3 MF-iPSCs. Results are means ± SD. ANOVA test: *P < .05, **P < .01, ***P < .001.