Effect of epidermal chalones on growth of transplantable tumors

An alcoholic extract obtained from rat skin contains epidermal g1- and g2-chalones, and when added to a suspension of cells of a transplantable squamous-cell keratinizing carcinoma of the mouse cervix uteri it inhibits its growth by 72.6% when injected into recipient mice. The extract had no inhibitory action on transplantable mouse tumors of other histogenesis (hepatoma 22a, leukemia L-1210, and sarcoma 180). Epidermal chalones had only weak action (inhibiting growth by 39.2%; P>0.05) on an anaplastic transplantable mouse skin carcinoma, which had lost its primary squamous-cell structure in the course of prolonged passage (more than 10 years).