H-ras is a proto-oncogen related with cancer processes, whose mutations are also markers of the very rare disease named Costello Syndrome. P19 H-Ras regulates the cell cycle and also the expression of the mir-342, mir-206, mir-330, mir-138 and mir-99b. Few are known about the function of these miRNAs, but miR-206 and miR-342 have been related or are markers of breast cancer and APL (acute promyelocytic leucemia), respectively. The main objective of this line is to study miRNAs related or regulated by the two proteins H-Ras (p19 and p21): i) To know more about the function of the mir-342, mir-206, mir-330, mir-138 y mir-99b will be one of the objectives of this line; ii) A second objective is also to study whether p21 also regulates the p19 related miRNAs (mir-342, mir-206, mir-330, mir-138 y mir-99b); iii) To study whether the D intron (between exons 3 and 4A of H-Ras) contains or not any new intronic precursors of miRNA and more specifically, whether the stem-loop IDX-rasISS1 also may render an intronic miRNA precursor ; iv) to know whether p19 may regulate the p68 RNA helicase through the miR-206 and v) To study the function of FUS/TLS and hnRNP H as regulators of the alternative splicing of H-Ras. The study of miRNAs are just at the infancy, however it is expected that they will render an important change on several diseases as AIDS, Alzheimer, cancer, etc. The knowledge of the miRNAs here studied will be the base for bieng therapeutic targets for cancer processes and Costello Syndrome. Furthermore, the studies here proposed will render a general vision about all the miRNAs codified by the gen H-ras and about the metabolic network that is regulated by all the messages (protein and miRNAs) obtained from the gen H-ras.