In higher plants, homeobox genes of the KNOX and WOX subfamilies plays a key role in maintenance of the pool of stem cells, regulate proliferation, and prevent cell differentiation. It has been shown that meristem-specific genes are regulated by phytohormones and affect their metabolism, specifically that of cytokinins. Plant tumors are widely used as a model for studying the genetic control of cell division and differentiation. The tumors induced by pathogens and genetic tumors, whose development depends on the plant genotype, are distinguished. The changes in the levels of expression of genes--regulators of cell cycle, meristem-specific genes, and genes controlling metabolism and transmission of the signal of phytohormones were described on tumors of different origin. The mechanisms underlying tumor formation in plants and animals were shown to be similar, specifically as concerns the relationship between the genes--cell cycle regulators and tumorigenesis. In plants, transcriptional factors of the subfamily KNOX have similarity in structure and, supposedly, common origin with transcriptional factors MEIS in animals, which are very active in neoplastic cells. The review presents the characteristics of KNOX and WOX transcriptional factors, their functions in meristem development, and interaction with the plant hormonal system. The role of homeodomain-containing transcriptional factors in tumorigenesis in plants and animals is discussed. The role of meristem-specific genes and phytohormones in tumorigenesis is discussed on the example of genetic tumors obtained by mutagenesis in Arabidopsis thaliana and tumors in the radish inbred lines.