Fruit size in apple (Malus x domestica) is of great economic significance. A thorough comprehension of mechanisms that regulate fruit growth and development is essential to optimize fruit size. In this study, the factors affecting shade-induced and thinning-induced alteration in fruit growth were determined. The results demonstrate that shade-induced reduction in fruit growth and thinning-induced increase in fruit growth is facilitated by coordinated changes in the expression of carbohydrate metabolism-related genes, transcription factors associated with fruit growth, and key genes associated with cell production and expansion. The changes in the expression of these genes may regulate fruit growth by altering the key processes of cell production and expansion. AINTEGUMENTA (ANT), an AP2 domain transcription factor, controls organ size in Arabidopsis by regulating the duration of cell production and is a candidate for fruit growth regulation in apple. Two genes homologous to the Arabidopsis ANT, MdANT1 and MdANT2, were isolated from apple. The expression of these genes was analyzed during fruit development, in response to factors affecting fruit size, and across genotypes. The results demonstrate that the expression of these ANTs is closely associated with cell production during fruit development. Additionally, wild-type Arabidopsis plants were transformed with Act7::MdANT1/2 and Act2::GFP:MdANT1/2 constructs. The transgenic plants obtained can be used for functional characterization of MdANT1 and MdANT2, to determine their roles in regulating organ size in plants.