Genes play an essential role in determining an organism’s physical attributes, including the formation of ears and tails. While humans do not naturally have cat ears or tails, it is possible to create these structures through genetic modification. Here are some additional genes and their functions that could be useful in the process of creating cat ears and tails in humans.

Ear Formation:
1. SHH (Sonic Hedgehog) - This gene is responsible for the development of the midline of the embryo, including the formation of the ear. Mutations in this gene can lead to anomalies such as cyclopia and abnormal ear development.
2. PAX8 - This gene regulates the expression of other genes during ear formation, including the differentiation of sensory cells in the inner ear.
3. SOX9 - This gene is necessary for the development of the ear’s cartilage and the maturation of its sensory cells.
4. FGF (Fibroblast Growth Factors) - FGFs are a family of genes that regulate the growth, differentiation, and migration of cells during ear development.
5. NOTCH - This gene plays a role in ear development by regulating cell fate decisions, including determining the number and type of cells in the inner ear.
6. HOX genes - HOX genes are responsible for the patterning of the embryo in the anterior-posterior axis and are involved in the formation of the ear’s shape.

Tail Formation:
1. Wnt - This gene regulates the growth and development of the dorsal (top) and ventral (bottom) sides of the embryo, including the formation of the tail.
2. BMP (Bone Morphogenetic Protein) - This gene plays a substantial role in determining embryonic development and is responsible for the creation of limbs, the spinal cord, and the tail.
3. CDX (Caudal-Related Transcription Factor) - This gene controls the expression of other genes involved in hindgut and tail development. It is also expressed in the tail bud and is critical for tail elongation.
4. TBXT (T-box transcription factor T) - This essential gene helps regulate the development of the embryonic germ layers, including the formation of tail structures in the embryo.
5. WNT3A - Like Wnt, this gene is also involved in tail formation. WNT3A induces the expression of Hox genes in the tail bud, critical for proper tail elongation and dorsoventral patterning.

In descending order of importance, the genes for ear formation that can be useful in this task are: SHH, PAX8, SOX9, FGF, NOTCH, and HOX genes. SHH plays a significant role in the midline development of the embryo, which includes ear formation, while PAX8 and SOX9 regulate the expression of other genes involved in ear development. FGF, NOTCH, and HOX genes are also essential for cell growth, differentiation, and motor control within the ear.

In descending order of importance, the order of the genes for tail formation that can be useful in this task will be: Wnt, BMP, TBXT, CDX, and Wnt3a. Wnt and BMP play critical roles in dorsal and ventral embryo growth, tail formation, and the creation of limbs and spinal cord. TBXT controls the expression of other tail growth genes, including the Wnt gene family, while CDX is involved in elongation. Wnt3a contributes to tail elongation and dorsoventral patterning, but it might not be as essential as some of the other genes listed above.

It is important to note that performing genetic modification on humans can raise ethical and safety concerns. The possibility of creating cat ears and tails in humans is purely hypothetical, and should only be attempted with ethical and scientific considerations. Nevertheless, the identification of these genes provides essential clues concerning the intricate molecular events underlying the formation of specialized organs in developing organisms.

please confirm the functions of these proteins with references to scientific papers