Sonic the Hedgehog different media including animation, comic books, and a Hollywood film. The first "Sonic" game, "Sonic the Hedgehog", is a platform game released in 1991. Players control the anthropomorphic blue hedgehog Sonic, who can run and jump at high speeds using springs, ramps, and loops. Sonic must stop Dr. Robotnik from taking over the world using the Chaos Emeralds. "Sonic the Hedgehog 2" (1992) increased the overall size and speed of the series' gameplay and was the second best-selling Genesis game. It introduced Sonic's sidekick and best friend, Miles "Tails" Prower, who followed Sonic throughout the game, and allowed a second
Sonic hedgehog are thought to be successively patterned throughout the neural tube by the SHH concentration gradient. Mutual inhibition between pairs of transcription factors expressed in neighboring domains contributes to the development of sharp boundaries, however, in some cases, inhibitory relationship has been found even between pairs of transcription factors from more distant domains. Particularly, NKX2-2 expressed in the V3 domain is reported to inhibit IRX3 expressed in V2 and more dorsal domains, although V3 and V2 are separated by a further domain termed MN. Sonic hedgehog (SHH) is a signaling molecule that is encoded by the same gene sonic hedgehog. SHH