The microRNA cluster including Mir141 and Mir200c was replaced via homologous recombination with a puromycin/thymidine kinase fusion gene under the control of EM7/PGK promoters. The inserted selection cassette was flanked by LoxP and F3/FRT sites. The deletion starts at position 124718404 and ends at position 124717909 of Chromosome 6 (Genome Build 38). (J:94077, J:174268)