- The tuberous sclerosis-1 (TSC1) gene product hamartin suppresses cell growth and augments the expression of the TSC2 product tuberin by inhibiting its ubiquitination. Benvenuto, G., Li, S., Brown, S.J., Braverman, R., Vass, W.C., Cheadle, J.P., Halley, D.J., Sampson, J.R., Wienecke, R., DeClue, J.E. Oncogene (2000)