Melanoma is an extremely aggressive form of skin cancer that can spread to the lungs, brain, and liver, among other vital organs. Melanoma cells, unlike any other cancer cells, can produce significant amounts of melanin by a process known as melanogenesis, causing them to become heavily pigmented. Melanogenesis, specifically the melanin pigment, is well known for its ability to protect the skin from the harmful effects of UV light, which can lead to the development of skin cancer. Nevertheless, uncontrolled melanogenesis plays a role in the advancement of melanotic melanoma, and melanin pigments can reduce the effectiveness of radiotherapy and immunotherapy. Therefore, studies are being performed that focus on inhibiting melanogenesis to prevent melanoma metastasis. However, it is worth noting that, in addition to its UV‑protective function, melanin also plays a role in preventing melanoma metastasis. Microphthalmia‑associated transcription factor (MITF) and melanin have been demonstrated to attenuate the aggressiveness of melanoma by suppressing numerous essential metastatic processes. Eumelanin and pheomelanin (two types of melanin), which cause oxidative stress, can also prevent melanoma progression in the early stages. Hence, it is vital to explore the role of inducing melanogenesis rather than inhibiting melanogenesis in preventing melanoma metastasis.

Eye color is determined as a polymorphism and polygenic trait. Brown is the most common eye color in the world, accounting for about 79%, blue eye color for about 8-10%, hazel for 5%, and green for 2%. Rare-colored eyes include gray and red/violet. Different factors are involved in determining eye color. The two most important factors are the iris pigment and the way light is scattered from the iris. Gene expression determines the iris pigmentation and how much melanin is present in the eye, which is the number of melanin subunits that identify eye color. The genes involved in the pigmentation of single-nucleotide polymorphism (SNP) have a significant role; and even some genes are included only in the eye color through SNP. MicroRNAs also affect melanocyte synthesis, which is usually affected by the downregulation of essential genes involved in pigmentation. In this study, we assess the biochemical pathways of melanin synthesis, and the role of each gene in this pathway also has been examined in the signaling pathway that stimulates melanin synthesis.

Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their \'mouldic impressions\') as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues. We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils.